Dissertations / Theses on the topic 'Optical Frequency Comb (OFC)'
To see the other types of publications on this topic, follow the link: Optical Frequency Comb (OFC).
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Optical Frequency Comb (OFC).'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Doumbia, Yaya. "Optical injection dynamics and polarization properties of semiconductor lasers frequency combs." Electronic Thesis or Diss., CentraleSupélec, 2021. http://www.theses.fr/2021CSUP0008.
Full textAbstract:
Dans ce travail, nous étudions la dynamique non linéaire de diodes laser injectées optiquement avec des peignes de fréquence.Nous analysons d'abord théoriquement et expérimentalement la dynamique non linéaire des lasers à émettant par la tranche (EELs) à partir d'une injection optique de peignes de fréquence. Les paramètres d'injection et les propriétés du peigne injecté sont variés pour dévoiler plusieurs dynamiques verrouillées et déverrouillées. Pour une force d'injection suffisamment grande et sur une large plage de désaccord, le verrouillage d'injection bifurque vers une dynamique temporelle correspondant à un peigne de fréquence optique qui étend le peigne injecté à un spectre optique beaucoup plus large. Une analyse de bifurcation révèle une dynamique de peigne de fréquence harmonique en cascade conduisant à une augmentation significative des lignes de peigne de sortie. Nous avons également utilisé les paramètres d'injection, les propriétés du peigne et le courant d'injection pour contrôler les propriétés du nouve peigne. Dans un deuxième temps, nous analysons expérimentalement la dynamique non linéaire et les propriétés de polarisation dans des lasers émettant par la surface (VCSEL) soumis à une injection optique orthogonale avec des peignes de fréquence. Plus important encore, le VCSEL montre deux peignes de fréquence avec une polarisation orthogonale à partir d'un seul appareil pour certains paramètres d'injection. Nous démontrons également la possibilité de contrôler le taux de répétition des peignes à une ou deux polarisations grâce à la génération de peignes à fréquence harmonique. Nous présentons enfin expérimentalement et théoriquement la dynamique d'injection de VCSEL à partir d'une injection de peigne de fréquence optique avec une polarisation parallèle à celle du VCSEL. Nous montrons que la performance des peignes à deux polarisations sont limitées à une injection de courant élevé dans le cas d'une injection optique parallèle. Pour un courant de polarisation fixe, la dynamique des deux peignes de polarisation disparaît lorsque l'on augmente l'espacement des peignes injectés.Cette thèse démontre donc outre son intérêt pour la dynamique laser non linéaire, l'injection optique est une technique permettant d'exploiter les propriétés de peigne dans les diodes laserIn this work, we study the nonlinear dynamics of laser diodes optically injected with frequency combs.We first theoretically and experimentally analyze the nonlinear dynamics of edge-emitting lasers (EELs) from an optical injection of frequency combs. The injection parameters and injected comb properties are varied to unveil several locked and unlocked dynamics. For large enough injection strength and over a large detuning range, the injection locking bifurcates to a time-periodic dynamics corresponding to an optical frequency comb that extends the injected comb to a much broader optical spectrum. A bifurcation analysis reveals a cascade harmonic frequency comb dynamics leading to a significant increase in the output comb lines. We have also used the injection parameters, comb properties, and injection current to control the new comb properties. We secondly analyze the nonlinear dynamics and polarization properties in vertical-cavity surface-emitting lasers (VCSELs) subject to orthogonal optical injection with frequency combs experimentally. Most importantly, the VCSEL shows two frequency combs with orthogonal polarization from a single device for some injection parameters. We also demonstrate the possibility to control the single or two polarizations comb repetition rate through harmonic frequency combs generation. We finally present experimentally and theoretically the VCSEL injection dynamics from parallel optical frequency comb injection. We show that the two polarizations combperformance is restricted to high current injection in the case of parallel optical injection. For fixed bias current, the two polarization comb dynamics disappear when increasing the injected comb spacing.This thesis therefore demonstrates besides its interest for nonlinear laser dynamics, optical injection is a technique to harness the comb properties in laser diodes
2
Brother, Louis Reginald. "Terahertz optical frequency comb generation." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10746.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (leaves 191-195).
by Louis Reginald Brothers, Jr.
Ph.D.
3
Wu, David S. "Optical frequency comb locked signal synthesis." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/375133/.
Full textAbstract:
Highly stable optical frequency combs (OFCs), particularly those generated by modelocked lasers, have become important tools for frequency and time metrology, and spectroscopy. This is due to their ability to span wide bandwidths, to act as highly accurate frequency references, and to provide a direct link between the optical and radio frequencies. However, the narrow comb spacing of most mode-locked OFCs makes it difficult to access their individual modes for a wide range of other potential applications. This thesis investigates comb mode extraction from a 250 MHz spaced OFC by phase locking semiconductor lasers (slave lasers) to individual comb modes. This was achieved using optical injection locking in combination with a low bandwidth electronic feedback loop. The locking process forced a slave laser to emit at the same frequency as the comb mode it was locked to, but at its natural output power. Hence a locked slave laser effectively behaved as a ultra-narrowband filter with active gain. The locking process was characterised in terms of its long-term frequency stability over a period of 8 hours (minimum Allan deviation of less than 10-18) and its short term phase noise across a bandwidth from 100 Hz to 500 MHz (minimum integrated phase noise of 0.02 rad2). Amplification of the residual comb modes was measured and found to have a dependence on the master-slave frequency detuning. The results from numerical modelling found that this was due to phase modulation induced in the slave laser by the injected OFC and could always be suppressed by controlling the frequency detuning. Fourier synthesis of high repetition rate waveforms was explored as one of the potential applications of this phase locking technique. Multiple lasers were made coherent with one another by locking them to different modes of a common OFC. This enabled them to behave as different frequency components of a Fourier series to generate various waveforms. This was achieved by independently controlling the relative amplitude and phase of each slave laser, and combining them together. The generation of stable waveforms with at-top, triangular, parabolic, and sawtooth intensity profiles was demonstrated at a repetition rate of 100 GHz.
4
Del'Haye, Pascal. "Optical Frequency Comb Generation in Monolithic Microresonators." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-130491.
Full text
5
Cai, Yin. "Quantum coherent control with an optical frequency comb." Thesis, Paris, Ecole normale supérieure, 2015. http://www.theses.fr/2015ENSU0030/document.
Full textAbstract:
Les états quantiques multimodes sont au coeur des protocoles detraitement quantique de l’information et de métrologie quantique. Àpartir d’un peigne de fréquence optique injectant un oscillateurparamétrique optique pompé en mode synchrone (SPOPO) nousavons généré des états multimodes en temps/fréquence. Unsimulateur quantique est alors mis en place à partir de ce SPOPO et demise en forme d’impulsion, et permet de mettre en évidence de étatsclusters pouvant compter jusque 12 noeuds et un protocole departage de secret quantique à six partenaires. De plus, une détectionmultipixel résolue en fréquence est développée et utilisée pourréaliser un état cluster linéaire à 8 noeuds. Nous avons égalementutilisé cette source pour développer un spectromètre ayant unesensibilité allant au delà de celle imposée par les fluctuations du videquantiqueMultimode squeezing plays an essential role in quantum informationprocessing and quantum metrology. Using optical frequency combs,we generate multi-temporal-mode state from a synchronouslypumped optical parametric oscillator (SPOPO). An on-demandquantum network simulator is developed using the SPOPO andultrafast pulse shaping; up-to-twelve-node cluster states and asix-partite quantum secret sharing protocol are experimentallyemulated with this simulator. Furthermore, frequency resolvedmultipixel detectors are employed, and used to realize aline-shape-eight-node cluster state. We also developed a multimodequantum spectrometer, which is able to exceed the standardquantum limit for measuring manifold parameters of ultrafast pulses
6
Seton, Ragnar. "Data acquisition system for optical frequency comb spectroscopy." Thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-139117.
Full textAbstract:
The Optical Frequency Comb Spectroscopy (OFCS) Group at the Department of Physics at Umeå University develops new techniques for extremely high sensitivity trace gas detection, non invasive temperature measurements, and other applications of OFCS. Their setup used primarily for trace gas detection contains several components that have been developed in-house, including a Fourier Transform Spectrometer (FTS) and an auto-balancing detector. This is the one used in this thesis work and it includes a high frequency data acquisition card (DAC) recording interferograms in excess of 10^7 double-precision floating point samples per sweep of the FTS's retarder. For acquisition and analysis to be possible in both directions of the retarder the interferograms needs to be analysed in a sub-second timeframe, something not possible with the present software. The aim of this thesis work has thus been to develop a system with optimized analysis implementations in MATLAB. The latter was a prerequisite from the group to ensure maintainability, as all members are well acquainted with it.Fulfilling its primary purpose MATLAB performs vector and matrix computations quite efficiently, has mostly fully mutable datatypes, and with recent just-in-time (JIT) compilation optimizations vector resizing performance has improved to what in many instances is perceived as equivalent to preallocated variables. This memory management abstraction, however, also means that explicit control of when arguments are passed by value or by reference to a function is not officially supported. The following performance ramifications naturally increase with the size of the data sets (N) passed as arguments and become quite noticeable even at moderate values of N when dealing with data visualization, a key function in system. To circumvent these problems explicit data references were implemented using some of the undocumented functions of MATLAB's libmx library together with a custom data visualization function.The main parts of the near real time interferogram analysis are resampling and a Fourier transformation, both of which had functionally complete but not optimized implementations. The minimal requirement for the reimplementation of these were simply to improve efficiency while maintaining output precision.On experimentally obtained data the new system's (DAQS) resampling implementation increased sample throughput by a factor of 19 which in the setup used corresponds to 10^8 samples per second. Memory usage was decreased by 72% or in terms of the theoretical minimum from a factor 7.1 to 2.0. Due to structural changes in the sequence of execution DAQS has no corresponding implementation of the reference FFT function as the computations performed in it have been parallelized and/or are only executed on demand, their combined CPU-time can however in a worst-case scenario reach 75% of that of the reference. The data visualization performance increase (compared to MATLAB's own, as the old system used LabVIEW) depends on the size in pixels of the surface it is visualized on and N, decreasing with the former and increasing with the latter. In the baseline case of a default surface size of 434x342 pixels and N corresponding to one full sweep of the FTS's retarder DAQS offers a 100x speed-up to the Windows 7 version of MATLAB R2014b's plot.In addition to acquiring and analyzing interferograms the primary objectives of the work included tools to configure the DAC and controlling the FTS's retarder motor, both implemented in DAQS.Secondary to the above was the implementation of acquisition and analysis for both directions of the retarder, a HITRAN reference spectra generator, and functionality to improve the user experience (UX). The first, though computation time allows for it, has not been implemented due to a delay in the DAC-driver. To provide a generic implementation of the second, the HITRAN database was converted from the text-based format it is distributed in to a MySQL database, a wrapper class providing frequency-span selection and the absorption spectra generation was developed together with a graphical front-end. Finally the improved UX functionality mainly focused on providing easy-access documentation of the properties of the DAC.In summation, though the primary objectives of optimizing the data analysis functions were reached, the end product still requires a new driver for the DAC to provide the full functionality of the reference implementation as the existing one is simply too slow. Many of DAQS' components can however be used as stand-alone classes and functions until a new driver is available. It is also worth mentioning that National Instruments (NI), the DAC vendor, has according to their technical support no plans to develop native MATLAB drivers as MathWorks will not sell them licenses.
7
Marian, Adela Ye Jun. "Direct frequency comb spectroscopy for optical frequency metrology and coherent interactions." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/dissertations/fullcit/3186934.
Full text
8
Buettner, Thomas Frank Sebastian. "Brillouin Frequency Comb Generation in Chalcogenide Waveguides." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14447.
Full textAbstract:
Compact optical frequency comb sources with gigahertz repetition rates are desirable for various important applications including arbitrary optical waveform generation, microwave synthesis, spectroscopy and advanced telecommunications. This thesis investigates the exploitation of the interplay of two distinct nonlinear optical effects for the generation of gigahertz repetition rate frequency combs: stimulated Brillouin scattering (SBS) and the optical Kerr-effect. This interplay can lead to the generation of Brillouin frequency combs (BFCs) with repetition rates that are equal to the acoustic resonance associated with SBS. This resonance frequency is about 8 GHz, making BFCs ideal for the advanced photonic applications of interest. In this thesis, we experimentally demonstrate BFCs with equally spaced comb modes that exhibit a stable and repeatable spectral phase. The BFCs are generated in chalcogenide fibre and in chalcogenide waveguides on photonic chips. Through theoretical and numerical investigations we show that, whilst SBS provides the high repetition rate of the combs, the Kerr-nonlinearity plays an important role in achieving equally spaced and phase-coherent spectral components. We also study the interplay of BFCs and photosensitivity via multiphoton absorption in chalcogenide fibres and photonic chips. We show that this interplay can be used to internally inscribe multiwavelength gratings that exhibit several stopbands that are spaced by the acoustic resonance frequency. We then use these gratings in an SBS configuration and demonstrate a significant enhancement of BFC generation by exploiting the slow light effects associated with the grating band edges. This body of work represents an advance in the understanding of BFCs. We study the physics behind phase-coherent BFC generation. The demonstration of chip-based BFC generation is a step towards an all integrated, gigahertz repetition rate, optical frequency comb source. We also demonstrate a novel and flexible method for enhancing chip-based BFC generation that can potentially be extended to other nonlinear effects.
9
Del´Haye, Pascal [Verfasser]. "Optical Frequency Comb Generation in Monolithic Microresonators / Pascal Del´Haye." München : Verlag Dr. Hut, 2011. http://d-nb.info/1013526236/34.
Full text
10
Rydberg, Olof. "Stabilization of an optical frequency comb to an external cavity." Thesis, Umeå universitet, Institutionen för fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-93439.
Full textAbstract:
The subject of this master's thesis is stabilizing a frequency comb laser to an external cavity using a couple of servo controllers. The aim of the project was to build a pair of servo controllers, replacing parts of the existing commercial and proprietary solution already in use. The system under control is an optical frequency comb, which is locked to an external cavity and is used for trace gas detection and spectroscopy. The comb is a broadband light source and needs to be locked to the external cavity in order to achieve maximum transmission through the cavity. The goal was to replace two of the original controllers and try to improve the locking capabilities of the system. The controllers were also supposed to be customizable and for that reason the control system with all its components was built on breadboards and confined in an aluminium box. Control circuits were built for the purpose, one for controlling the comb offset frequency by modulating the pump diode current, the other for controlling the repetition rate of the comb laser by altering the length of the laser cavity using a piezo-electric transducer (PZT). A commercial and proprietary servo controller was also in the system, controlling an intra-cavity electro-optic modulator. It was kept for controlling the higher frequency region, for which the PZT no longer worked. In order to simulate and design the system, Matlab was used with functions described by both theoretically and experimentally obtained mathematical equations. The controllers were tested thoroughly in order to make sure they acted according to the intended design, before they were tested with the laser. After an initial lock was obtained, the controllers were optimized further using both experimental and theoretical methods until the lock was optimized and the transmission through the cavity was maximized. The error signals that were used for controlling the system were monitored with both an oscilloscope and a spectrum analyser, the latter producing a spectrum with the power ratio plotted versus frequency. The transmission intensity through the cavity was measured when a good lock had been achieved and the results were analysed by applying a Fourier transform to the measured data. This was done with both the old controllers and the new controllers and the resulting plots were compared. Analysis showed that the new control system yielded a transmission signal with a slightly reduced noise level compared to the signal resulting from using the old controllers. The results from the spectrum analyser also showed slightly reduced error signals for the new controllers compared to those of the old controllers. When summarising this work it can be concluded that the goals set up at the start were achieved with results living up to the expectations. The results also verified that such a control system can be built for locking an optical frequency comb to an external cavity with simple and rather cheap components and with good results.
11
Pfeifle, Jörg [Verfasser]. "Terabit-Rate Transmission Using Optical Frequency Comb Sources / Jörg Pfeifle." Karlsruhe : KIT Scientific Publishing, 2017. http://www.ksp.kit.edu.
Full text
12
Zajnulina, Marina [Verfasser], and Martin M. [Akademischer Betreuer] Roth. "Optical frequency comb generation in optical fibres / Marina Zajnulina ; Betreuer: Martin M. Roth." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218400218/34.
Full text
13
Shen, Pengbo. "Optical frequency comb generator and millimetre-wave photonic local-oscillator systems." Thesis, University of Kent, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445795.
Full text
14
Wu, Chunbai 1980. "Raman optical frequency comb generation in hydrogen-filled hollow-core fiber." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/11052.
Full textAbstract:
xiv, 138 p. : ill. (some col.)In this dissertation, we demonstrate the generation of optical Raman frequency combs by a single laser pump pulse traveling in hydrogen-filled hollow-core optical fibers. This comb generation process is a cascaded stimulated Raman scattering effect, where higher-order sidebands are produced by lower orders scattered from hydrogen molecules. We observe more than 4 vibrational and 20 rotational Raman sidebands in the comb. They span more than three octaves in optical wavelength, largely thanks to the broadband transmission property of the fiber. We found that there are phase correlations between the generated Raman comb sidebands (spectral lines), although their phases are fluctuating from one pump pulse to another due to the inherit spontaneous initiation of Raman scattering. In the experiment, we generated two Raman combs independently from two fibers and simultaneously observed the single-shot interferences between Stokes and anti-Stokes components from the two fibers. The experimental results clearly showed the strong phase anti-correlation between first-order side bands. We also developed a quantum theory to describe this Raman comb generation process, and it predicts and explains the phase correlations we observe. The phase correlation that we found in optical Raman combs may allow us to synthesize single-cycle optical pulse trains, creating attosecond pulses. However, the vacuum fluctuation in stimulated Raman scattering will result in the fluctuation of carrier envelope phase of the pulse trains. We propose that we can stabilize the comb by simultaneously injecting an auxiliary optical beam, mutually coherent with the main Raman pump laser pulse, which is resonant with the third anti-Stokes field.
Committee in Charge: Dr. Steven van Enk, Chair; Dr. Michael G. Raymer; Dr. Daniel A. Steck; Dr. David M. Strom; Dr. Andrew H. Marcus
15
Lessing, Maurice. "Ultra-low-noise frequency synthesis, comparison and dissemination using femtosecond optical frequency combs." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/8514.
Full textAbstract:
This thesis presents research into ultra-low noise photonic microwave synthesis and the development of a novel, frequency comb-based, fibre optic time transfer technique. The focus in the first area is on reducing the noise introduced in the optical-to- electrical conversion process using balanced optical-microwave phase detectors. Two mainly free-space and two mainly fibre-based devices were built and their performance was characterised. The phase noise of the optical-to-electrical conversion of the free-space device was -119 dBc Hz⁻¹ at 1 Hz and -143 dBc Hz⁻¹ at 20 kHz from an 8 GHz carrier which is the best performance reported for a free-space balanced-optical microwave phase detector. The improved fibre-based set-ups demonstrated a state-of-the-art amplitude-to-phase noise suppression of 60 dB and a phase noise of the optical-to-electrical conversion of -131 dBc Hz⁻¹ at 1 Hz and 148 dBc Hz⁻¹ at 20 kHz from an 8 GHz carrier. The novel time transfer technique developed in the second part superimposes timing information onto the optical pulse train of an ITU-channel-filtered frequency comb using an intensity modulation scheme. Time transfer over a 50 km long, delay-stabilised fibre spool produced a state-of-the-art time deviation of 300 fs and an accuracy of approximately 0.01 ns which is close to the best performance achieved using amplitude modulated cw lasers. Using this technique on a 159 km long installed fibre link between NPL and Reading, the same time deviation was achieved and an accuracy of approximately 0.08 ns was obtained, limited by uncertainty of the time interval counter. Using the same fibre link, microwave frequency transfer of the ITU-channel-filtered comb was demonstrated with a fractional frequency instability of 2x10⁻¹⁷ at 5000 s which is approximately at the same level as the best previously reported results which were obtained with a 30 nm wide optical frequency comb.
16
Paschke, Anna-Greta [Verfasser]. "9Be+ ion qubit control using an optical frequency comb / Anna-Greta Paschke." Hannover : Technische Informationsbibliothek (TIB), 2017. http://d-nb.info/1149693614/34.
Full text
17
Turghun, Matniyaz. "Free-space NPR mode locked erbrium doped fiber laser based frequency comb for optical frequency measurement." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18682.
Full textAbstract:
Master of ScienceDepartment of Physics
Brian R. Washburn
This thesis reports our attempt towards achieving a phase stabilized free-space nonlinear polarization rotation (NPR) mode locked erbium doped fiber laser frequency comb system. Optical frequency combs generated by mode-locked femtosecond fiber lasers are vital tools for ultra-precision frequency metrology and molecular spectroscopy. However, the comb bandwidth and average output power become the two main limiting elements in the application of femtosecond optical frequency combs. We have specifically investigated the free-space mode locking dynamics of erbium-doped fiber (EDF) mode-locked ultrafast lasers via nonlinear polarization rotation (NPR) in the normal dispersion regime. To do so, we built a passively mode-locked fiber laser based on NPR with a repetition rate of 89 MHz producing an octave-spanning spectrum due to supercontinuum (SC) generation in highly nonlinear fiber (HNLF). Most significantly, we have achieved highly stable self-starting NPR mode-locked femtosecond fiber laser based frequency comb which has been running mode locked for the past one year without any need to redo the mode locking. By using the free-space NPR comb scheme, we have not only shortened the cavity length, but also have obtained 5 to 10 times higher output power (more than 30 mW at central wavelength of 1570 nm) and much broader spectral comb bandwidth (about 54 nm) compared to conventional all-fiber cavity structure with less than 1 mW average output power and only 10 nm spectral bandwidth. The pulse output from the NPR comb is amplified through a 1 m long EDF, then compressed by a length of anomalous dispersion fiber to a near transform limited pulse duration. The amplified transform limited pulse, with an average power of 180 mW and pulse duration of 70 fs, is used to generate a supercontinuum of 140 mW. SC generation via propagation in HNLF is optimized for specific polling period and heating temperature of PPLN crystal for SHG around 1030 nm. At last, we will also discuss the attempt of second harmonic generation (SHG) by quasi phase matching in the periodically polled lithium niobate (PPLN) crystal due to nonlinear effect corresponding to different polling period and heating temperature.
18
Chen, Sophia Lee. "Two-Photon Direct Frequency Comb Spectroscopy of Rubidium." Oberlin College Honors Theses / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1337650567.
Full text
19
Schließer, Albert. "Cavity optomechanics and optical frequency comb generation with silica whispering-gallery-mode microresonators." Diss., München Hut, 2009. http://edoc.ub.uni-muenchen.de/10940/.
Full text
20
Hjältén, Adrian. "Modeling the cavity dispersion in cavity-enhanced optical frequency comb Fourier transform spectroscopy." Thesis, Umeå universitet, Institutionen för fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-157146.
Full textAbstract:
Cavity enhanced optical frequency comb spectroscopy is a technique that allows for quick and sensitive measurements of molecular absorption spectra. Locking the comb lines of an optical frequency comb to the cavity modes of an enhancement cavity and then extracting the spectral information with a Fourier transform spectrometer grants easy access to wide segments of absorption spectra. One of the main obstacles complicating the analysis of the measurements is the inevitable dispersion occurring inside the cavity. In this project, absorption measurements of CO2 were performed using an existing and well established setup consisting of a near-infrared optical frequency comb locked to a Fabry- Pérot enhancement cavity using the Pound-Drever-Hall technique, and a Fourier transform spectrometer. The purpose was to improve theoretical models of the measured absorption spectra by creating and verifying a model for the cavity dispersion, stemming mostly from the cavity mirrors but also from the normal dispersion of the intracavity medium. Until now, the cavity dispersion has been treated as an unknown and was included as a fitting parameter together with the CO2 concentration when applying fits to the absorption measurements. The dispersion model was based on previously performed precise measurements of the positions of the cavity modes. The model was found to agree well with measurements. In addition, pre-calculating the dispersion drastically reduced computation time and seemed to improve the overall robustness of the fitting routine. A complicating factor was found to be small discrepancies between the locking frequencies as determined prior to the measurements and the values yielding optimum agreement with the model. These apparent shifts of the locking points were found to have a systematic dependence on the distance between the locking points. The exact cause of this was not determined but the results indicate that with the locking points separated by more than about 10nm the shifts are negligible.
21
Ferreiro, Teresa I. "Development and characterisation of a near-infrared femtosecond optical parametric oscillator frequency comb." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2802.
Full textAbstract:
This thesis describes a 280 MHz MgO:PPLN-based optical parametric oscillator (OPO) synchronously pumped by a 50 fs Ti:sapphire laser to produce ultrafast pulses in the near-infrared. The OPO tuned over a wavelength range from 1450 - 1550 nm and 1624 - 1750 nm for the signal and idler respectively. The carrier-envelope-offset (CEO) frequency of the signal pulses was stabilised to a 10 MHz reference frequency without f-2f self-referencing, with an RMS phase variation of 0.56 rad over an observation time of 1 second. The relative intensity noise was measured for the CEO-stabilised OPO over an observation time of 64 seconds as 0.04%. The repetition frequency of the OPO was stabilised to 280 MHz using a frequency synthesiser at the eighth harmonic (2.24 GHz). This locking loop had an RMS phase variation of 0.98 mrad over a 1 second observation time. The CEO- and repetition frequencies were then locked simultaneously to a synthesiser referenced to a Rb-disciplined source, to generate a fully stabilised 1.5 μm frequency comb with an absolute uncertainty in comb mode position of 110 Hz. The upper limit for the fractional instability for a comb mode at 200 THz was found to be 2 x 10-11, limited by the stability of the Rb reference. A five-fold increase in comb mode spacing to 1.4 GHz was demonstrated with the stabilised frequency comb. This was achieved using a passive filter cavity, stabilised to a transmission peak via dither locking. The FWHM bandwidth of the optical spectrum for the filtered frequency comb was reduced to 8 nm, however no increase in comb linewidth was observed. An additional experiment was carried out where an external cavity diode laser was frequency-stabilised to a saturated absorption peak in Rb at 780.2 nm using dither locking, providing an optical frequency reference for future OPO frequency combs.
22
Fakhri, Maryam. "Near-infrared optical frequency comb Vernier spectroscopy in air and in a flame." Thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-132520.
Full textAbstract:
A Vernier spectrometer is built with a near-infrared mode-locked Er:doped fiber laser, a Fabry-Perot cavity with finesse of 1000, a diffraction grating and a photo detector. The optical cavity provides high sensitivity in absorption detection by enhancing the interaction length of the light with molecular species contained in the cavity. Coupling an optical frequency comb to the cavity provided a broadband spectral bandwidth with high precision to measure the absorption of several molecular species simultaneously. Also, by using the optical cavity as a filter, transmission of some bunch comb lines was achieved. This comb filtering together with a simple grating and a photodiode formed the Vernier detection technique to provide very fast measurements while it kept the setup very simple and compact. The system allows to detect carbon dioxide in the air and water vapor and OH radicals in the flame in a spectrum spanning from 1550 nm to 1590 nm, approximately. The retrieved spectrum has a resolution of 9.3 GHz being acquired in 0.05 s.
23
Parvex, Pichaida Taky. "Astrometric precision spectroscopy: Experimental development of a dual-frequency laser synthesizer based on an optical frequency comb." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/159288.
Full textAbstract:
Ingeniero Civil EléctricoLa tecnología de terahercios se encuentra en un estado de desarrollo atrasado con respecto a las tecnologías usadas en las bandas adyacentes, como la óptica infrarroja o la electróni- ca de microondas. En particular, no se poseen fuentes compactas de radiación que operen dentro esta banda logrando buenos niveles de potencia y amplios rangos de frecuencia. Las útiles propiedades de la radiación de terahercios como su capacidad de detectar moléculas complejas, buena resolución espacial y ser radiación no ionizante, hacen que el desarrollo de tecnología para esta banda sea un área con creciente interés. En el contexto del desarrollo de una nueva línea de investigación sobre espectroscopía molecular, en el Laboratorio de Terahertz y Astrofotónica de la Universidad de Chile, se realiza este trabajo que consiste en el desarrollo experimental de un sistema láser para la ali- mentación de fotomezcladores. Este sistema tiene como objetivo la generación de dos señales ópticas de alta estabilidad y coherencia, cuya diferencia de frecuencias puede ser ajustada de forma continua dentro del rango de 10 GHz a 300 GHz. Para esto, se utiliza un esquema basado en un peine de frecuencias óptico sobre el cual se enclava por inyección un láser de diodos de frecuencia sintonizable. Esto consigue tener una fuente infrarroja de alta precisión dentro de un gran rango. Además, se genera una segunda señal por medio de modulación en amplitud (AM), la cual es sintonizable dentro de un rango igual al espaciado producido por el peine óptico. En conjunto, estas señales logran abarcar un amplio espectro de frecuencias de forma continua sin perder estabilidad ni calidad de las señales. En este trabajo se logra implementar los subsistemas para la generación de cada una de las señales requeridas y se estudia la capacidad de estos para trabajar dentro del rango deseado. Para la señal generada por enclavamiento por inyección, se logra probar el concepto dentro de un rango reducido, principalmente por falta de un buen sistema de medición de altas frecuencias. Para la señal generada por modulación AM, se logran resultados positivos en todo el rango de diseño. Finalmente, se proponen modificaciones al sistema para mejorar su desempeño.
Este trabajo ha sido parcialmente financiado por Conicyt, a través de su fondo ALMA para el desarrollo de la astronomía, Proyecto 31140025, QUIMAL, Proyecto 1500010, CATA-Basal PFB06 y Fondecyt 1151213
24
Ozharar, Sarper. "STABLE OPTICAL FREQUENCY COMB GENERATION AND APPLICATIONS IN ARBITRARY WAVEFORM GENERATION, SIGNAL PROCESSING AND OPTICAL DATA M." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3516.
Full textAbstract:
This thesis focuses on the generation and applications of stable optical frequency combs. Optical frequency combs are defined as equally spaced optical frequencies with a fixed phase relation among themselves. The conventional source of optical frequency combs is the optical spectrum of the modelocked lasers. In this work, we investigated alternative methods for optical comb generation, such as dual sine wave phase modulation, which is more practical and cost effective compared to modelocked lasers stabilized to a reference. Incorporating these comblines, we have generated tunable RF tones using the serrodyne technique. The tuning range was ±1 MHz, limited by the electronic waveform generator, and the RF carrier frequency is limited by the bandwidth of the photodetector. Similarly, using parabolic phase modulation together with time division multiplexing, RF chirp extension has been realized. Another application of the optical frequency combs studied in this thesis is real time data mining in a bit stream. A novel optoelectronic logic gate has been developed for this application and used to detect an 8 bit long target pattern. Also another approach based on orthogonal Hadamard codes have been proposed and explained in detail. Also novel intracavity modulation schemes have been investigated and applied for various applications such as a) improving rational harmonic modelocking for repetition rate multiplication and pulse to pulse amplitude equalization, b) frequency skewed pulse generation for ranging and c) intracavity active phase modulation in amplitude modulated modelocked lasers for supermode noise spur suppression and integrated jitter reduction. The thesis concludes with comments on the future work and next steps to improve some of the results presented in this work.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
25
Ozharar, Sarper. "Stable optical frequency comb generation and applications in arbitrary waveform generation, signal processing and optical data mining." Orlando, Fla. : University of Central Florida, 2008. http://purl.fcla.edu/fcla/etd/CFE0002388.
Full text
26
Thapa, Rajesh. "Cr:forsterite laser frequency comb stabil[a]zation and development of portable frequency references inside a hollow optical fiber." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/994.
Full text
27
Silva, Claudio Fernandes Castanheira. "Dense WDM channel synthesis using optical frequency comb generation and locked laser filtering techniques." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399710.
Full text
28
Wan, Chenchen. "Low Noise Frequency Comb Sources Based on Synchronously Pumped Doubly Resonant Optical Parametric Oscillators." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1493915721069409.
Full text
29
Mondloch, Erin. "Quantum theory of conditional phonon states in a dual-pumped Raman optical frequency comb." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22793.
Full textAbstract:
In this work, we theoretically and numerically investigate nonclassical phonon states created in the collective vibration of a Raman medium by the generation of a dual-pumped Raman optical frequency comb in an optical cavity. This frequency comb is generated by cascaded Raman scattering driven by two phase-locked pump lasers that are separated in frequency by three times the Raman phonon frequency. We characterize the variety of conditioned phonon states that are created when the number of photons in all optical frequency modes except the pump modes are measured. Almost all of these conditioned phonon states are extremely well approximated as three-phonon-squeezed states or Schrödinger-cat states, depending on the outcomes of the photon number measurements. We show how the combinations of first-, second-, and third-order Raman scattering that correspond to each set of measured photon numbers determine the fidelity of the conditioned phonon state with model three-phonon-squeezed states and Schrödinger-cat states. All of the conditioned phonon states demonstrate preferential growth of the phonon mode along three directions in phase space. That is, there are three preferred phase values that the phonon state takes on as a result of Raman scattering. We show that the combination of Raman processes that produces a given set of measured photon numbers always produces phonons in multiples of three. In the quantum number-state representation, these multiples of three are responsible for the threefold phase-space symmetry seen in the conditioned phonon states.
With a semiclassical model, we show how this three-phase preference can also be understood in light of phase correlations that are known to spontaneously arise in single-pumped Raman frequency combs. Additionally, our semiclassical model predicts that the optical modes also grow preferentially along three phases, suggesting that the dual-pumped Raman optical frequency comb is partially phase-stabilized.
30
Ozdur, Ibrahim Tuna. "Low noise, narrow optical linewidth semiconductor-based optical comb source and low noise RF signal generation." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5009.
Full textAbstract:
Recently optical frequency combs and low noise RF tones are drawing increased attention due to applications in spectroscopy, metrology, arbitrary waveform generation, optical signal processing etc. This thesis focuses on the generation of low noise RF tones and stabilized optical frequency combs. The optical frequency combs are generated by a semiconductor based external cavity mode-locked laser with a high finesse intracavity etalon. In order to get the lowest noise and broadest bandwidth from the mode-locked laser, it is critical to know the free spectral range (FSR) of the etalon precisely. First the etalon FSR is measured by using the modified Pound-Drever-Hall (PDH) based method and obtained a resolution of 1 part in 106, which is 2 order of magnitude better than the standard PDH based method. After optimizing the cavity length, RF driving frequency and PDH cavity locking point, the mode-locked laser had an integrated timing jitter of 3 fs (1 Hz- 100 MHz) which is, to the best of our knowledge, the lowest jitter ever reported from a semiconductor based multigigahertz comb source. The mode-locked laser produces ~ 100 comb lines with 10 GHz spacing, a linewidth of ~500 Hz and 75 dB optical signal-to-noise ratio. The same system can also be driven as a regeneratively mode-locked laser with greatly improved noise performance. Another way of generating a low noise RF tone is using an opto-electronic oscillator which uses an optical cavity as a high Q element. Due to the harmonic nature of OEOs, a mode selection element is necessary. Standard OEOs use an RF filter having drawbacks such as broad pass band, high loss, and high thermal noise. In our work, a novel optoelectronic scheme which uses an optical filter (Fabry-Perot etalon) as the mode filter instead of an RF filter is demonstrated. This method has the advantage of having ultra-narrow filtering bandwidths ( ~ 10 kHz for a 10 GHz FSR and 10[super6] finesse) and an extremely low noise RF signal. Experimental demonstration of the proposed method resulted in a 5-10 dB decrease of the OEO noise compared to the conventional OEO setup. Also, by modifying the etalon-based OEO, and using single side band modulation, an optically tunable optoelectronic oscillator is achieved with 10-20 dB lower noise than dual side band modulation. Noise properties of the OEO as a function of optical frequency detuning is also analyzed theoretically and the results are in agreement with experimental results.
The thesis concludes with comments on future work and directions.ID: 029808830; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 98-106).
Ph.D.
Doctorate
Optics and Photonics
31
Lim, Jinkang. "All-fiber frequency comb employing a single walled carbon nanotube saturable absorber for optical frequency metrology in near infrared." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/7423.
Full textAbstract:
Doctor of PhilosophyDepartment of Physics
Brian R. Washburn
Optical frequency combs produced by mode-locked fiber lasers are useful tools for high precision frequency metrology and molecular spectroscopy in a robust and portable format. We have specifically investigated erbium doped fiber mode-locked lasers that use single-walled carbon nanotubes as a saturable absorber. We have, for the first time, developed and phase- stabilized a carbon nanotube fiber laser (CNFL) frequency comb. The carbon nanotube saturable absorber, which was fabricated using an optically driven deposition method, permits a high repetition frequency (>150 MHz) since an optical nonlinearity of fibers is not used for mode-locking. The CNFL comb combined with a parabolic pulse erbium doped fiber amplifier (EDFA) has shown a compact, robust, and cost-effective supercontinuum source. The amplified pulse from the parabolic pulse EDFA was compressed with a hollow-core photonic bandgap fiber, which produced a wave-breaking-free pulse with an all-fiber set-up. The stabilized comb has demonstrated a fractional instability of 1.2 ×10[superscript]-11 at 1 sec averaging time, the reference-limited instability. We have performed optical frequency metrology with the CNFL comb and have measured an optical frequency, P(13) which is a molecular overtone transition of C2H2. The measured frequency has shown a good agreement with the known value within an uncertainty of 10 kHz. In order to extend the application of the CNFL comb such as multi-heterodyne dual comb spectroscopy, we have investigated the noise of the CNFL comb and particularly, the broad carrier envelope offset frequency (f[subscript]0) linewidth of the CNFL comb. The primary noise source is shown to be white amplitude noise on the oscillator pump laser combined with the sensitivity of the mode-locked laser to pump power fluctuations. The control bandwidth of f[subscipt]0 was limited by the response dynamics of the CNFL comb. The significant reduction of comb noise has been observed by implementing a phase-lead compensation to extend control bandwidth of the comb and by reducing the pump relative intensity noise simultaneously. Therefore the f[subscipt]0 linewidth has been narrower from 850 kHz to 220 kHz. The integrated phase noise for the f[subscipt]0 lock is 1.6 radians from 100 Hz to 102 kHz.
32
Pasquali, González Elisa Co (Elisa Carolina) 1975. "Wideband optical frequency comb generator using a phase velocity-matched lithium tantalate electro-optic modulator." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47719.
Full textAbstract:
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (leaves 74-75).
A wideband optical frequency comb generator can be built using an electro-optic modulator that is driven at a frequency of several GHz and that is enclosed in an optical cavity. When light is circulated within the optical cavity, multiple passes through the modulator produce a spectrum centered at the carrier frequency with hundreds of sidebands spaced at the modulation frequency, with a comb span limited only by the material dispersion of the modulator. We present the design, construction, and testing of an optical frequency comb generator using lithium tantalate as a modulator substrate.
by Elisa C. Pasquali González.
M.Eng.
33
Marin-Palomo, Pablo [Verfasser], and C. [Akademischer Betreuer] Koos. "Chip-scale optical frequency comb sources for terabit communications / Pablo Marin-Palomo ; Betreuer: C. Koos." Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1238148093/34.
Full text
34
Panapakkam, Venkatesan Vivek. "Optical frequency comb generation using InP based quantum-dash/ quantum-well single section mode-locked lasers." Thesis, Evry, Institut national des télécommunications, 2016. http://www.theses.fr/2016TELE0024/document.
Full textAbstract:
Les interconnections optiques dans les fermes de données (data centers) nécessitent la mise au point de nouvelles approches technologiques pour répondre aux besoins grandissants en composants d’interface respectant des cahiers de charge drastiques en termes de débit, coût, encombrement et dissipation d’énergie. Les peignes de fréquences optiques sont particulièrement adaptés comme nouvelles sources optiques, à mêmes de générer un grand nombre de porteuses optiques cohérentes. Leur utilisation dans des systèmes de transmission en multiplexage de longueurs d’onde (WDM) et exploitant de nouveaux formats de modulation, peut aboutir à des capacités jamais atteintes auparavant. Ce travail de thèse s’inscrit dans le cadre du projet européen BIG PIPES (Broadband Integrated and Green Photonic Interconnects for High-Performance Computing and Enterprise Systems) et a pour but l’étude de peignes de fréquences générés à l’aide de lasers à verrouillage de modes, à section unique, à base de bâtonnets quantiques InAs/InP et puits quantiques InGaAsP/InP. Nous avons entrepris l’étude de nouvelles couches actives et conceptions de cavités lasers en vue de répondre au cahier des charges du projet européen. Une étude systématique du bruit d’amplitude et de phase de ces sources a en particulier été menée à l’aide de nouvelles techniques de mesure afin d’évaluer leur compatibilité dans des systèmes de transmission à très haut débit. Ces peignes de fréquences optiques ont été utilisées avec succès dans des expériences de transmission sur fibre optique avec des débits records dépassant le Tbit/s par puce et une dissipation raisonnable d’énergie par bit, montrant leur fort potentiel pour les applications d’interconnections optiques dans les fermes de donnéesThe increasing demand for high capacity, low cost, high compact and energy efficient optical transceivers for data center interconnects requires new technological solutions. In terms of transmitters, optical frequency combs generating a large number of phase coherent optical carriers are attractive solutions for next generation datacenter interconnects, and along with wavelength division multiplexing and advanced modulation formats can demonstrate unprecedented transmission capacities. In the framework of European project BIG PIPES (Broadband Integrated and Green Photonic Interconnects for High-Performance Computing and Enterprise Systems), this thesis investigates the generation of optical frequency combs using single-section mode-locked lasers based on InAs/InP Quantum-Dash and InGaAsP/InP Quantum-Well semiconductor nanostructures. These novel light sources, based on new active layer structures and cavity designs are extensively analyzed to meet the requirements of the project. Comprehensive investigation of amplitude and phase noise of these optical frequency comb sources is performed with advanced measurement techniques, to evaluate the feasibility of their use in high data rate transmission systems. Record Multi-Terabit per second per chip capacities and reasonably low energy per bit consumption are readily demonstrated, making them well suited for next generation datacenter interconnects
35
Kemal, Juned Nassir [Verfasser], and C. [Akademischer Betreuer] Koos. "Coherent terabit/s communications using chip-scale optical frequency comb sources / Juned Nassir Kemal ; Betreuer: C. Koos." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1215190395/34.
Full text
36
Khodabakhsh, Amir. "Fourier transform and Vernier spectroscopy using optical frequency combs." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-134439.
Full textAbstract:
Optical frequency comb spectroscopy (OFCS) combines two previously exclusive features, i.e., wide optical bandwidth and high spectral resolution, enabling precise measurements of entire molecular bands and simultaneous monitoring of multiple gas species in a short measurement time. Moreover, the equidistant mode structure of frequency combs enables efficient coupling of the comb power to enhancement resonant cavities, yielding high detection sensitivities. Different broadband detection methods have been developed to exploit the full potential of frequency combs in spectroscopy, based either on Fourier transform spectroscopy or on dispersive elements.There have been two main aims of the research presented in this thesis. The first has been to improve the performance of mechanical Fourier transform spectrometers (FTS) based on frequency combs in terms of sensitivity, resolution and spectral coverage. In pursuit of this aim, we have developed a new spectroscopic technique, so-called noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS), and achieved a shot-noise-limited sensitivity and low ppb (parts-per-billion, 10−9) CO2 concentration detection limit in the near-infrared range using commercially available components. We have also realized a novel method for acquisition and analysis of comb-based FTS spectra, a so-called sub-nominal resolution method, which provides ultra-high spectral resolution and frequency accuracy (both in kHz range, limited only by the stability of the comb) over the broadband spectral range of the frequency comb. Finally, we have developed an optical parametric oscillator generating a frequency comb in the mid-infrared range, where the strongest ro-vibrational molecular absorption lines reside. Using this mid-infrared comb and an FTS, we have demonstrated, for the first time, comb spectroscopy above 5 μm, measured broadband spectra of several species and reached low ppb detection limits for CH4, NO and CO in 1 s.The second aim has been more application-oriented, focused on frequency comb spectroscopy in combustion environments and under atmospheric conditions for fast and sensitive multispecies detection. We have demonstrated, for the first time, cavity-enhanced optical frequency comb spectroscopy in a flame, detected broadband high temperature H2O and OH spectra using the FTS in the near-infrared range and showed the potential of the technique for flame thermometry. For applications demanding a short measurement time and high sensitivity under atmospheric pressure conditions, we have implemented continuous-filtering Vernier spectroscopy, a dispersion-based spectroscopic technique, for the first time in the mid-infrared range. The spectrometer was sensitive, fast, robust, and capable of multispecies detection with 2 ppb detection limit for CH4 in 25 ms.Optisk frekvenskamspektroskopi (OFCS) kombinerar två tidigare icke förenliga egenskaper, dvs. ett brett optiskt frekvensområde med en hög spektral upplösning, vilket möjliggör noggranna mätningar av hela molekylära absorptionsband och detektion av flera gaser samtidigt med en kort mättid. Eftersom frekvenskammar har en regelbunden struktur med jämnt separerade laser moder kan man effektivt koppla kammen till en optisk kavitet och därmed möjliggöra frekvenskamsdetektion med hög känslighet. Olika metoder har utvecklats för att utnyttja frekvenskammarnas fulla potential för spektroskopi, baserad på antingen Fouriertransform-spektroskopi eller dispersiva element.Forskningen som presenteras i denna avhandling har haft två huvudmål. Det första har varit att förbättra prestandan hos mekaniska Fourier-transformspektrometrar (FTS) baserat på frekvenskammar med avseende på känslighet, upplösning och spektral täckning. I strävan efter detta har vi utvecklat en ny spektroskopisk teknik, benämnd brusimmun kavitetsförstärkt optisk frekvenskamspektroskopi (NICE-OFCS), och uppnått en hagelbrusbegränsad känslighet och detektionsgränser ner till låga ppb koncentrationer (miljarddelar, 10−9) för CO2 i det när-infraröda frekvensområdet enbart med användning av kommersiellt tillgängliga komponenter. Vi har också utvecklat en ny metod för insamling och analys av kambaserade FTS-spektra, som betecknas ha sub-nominell upplösning. Metoden gör det möjligt att uppnå ultrahög spektral upplösning och hög frekvensnoggrannhet (båda i kHz-området, endast begränsad av kammens stabilitet) över kammens hela frekvensområde. Slutligen har vi utvecklat en optisk parametrisk oscillator som genererar en frekvenskam i det mid-infraröda frekvensområdet, där de starkaste rotations-vibrationsmolekylära absorptionslinjerna finns. Med hjälp av denna kam och en FTS har vi för första gången demonstrerat frekvenskamspektroskopi över 5 μm. Vi har detekterat bredbandsspektra av flera molekylära gaser och har, för mättider på 1 s, uppnått detektionsgränser ner till låga ppb halter för CH4, NO och CO.Det andra syftet har varit mer applikationsorienterat: att använda frekvenskamspektroskopi i förbränningsmiljö och under atmosfäriska förhållanden för snabb och känslig multiämnesdetektion. Vi har för första gången demonstrerat kavitetsförstärkt optisk frekvenskamspektroskopi i en flamma, där vi har detekterat högtemperaturspektra av H2O och OH i det när-infraröda området med användning av FTS och visat teknikens potential för termometrisk karakterisering av flammor. För applikationer som kräver en kort mättid och hög känslighet under atmosfäriska förhållanden har vi utvecklat ett detektionssystem baserat på Vernier-spektroskopi med kontinuerlig filtrering, vilket är en dispersionsbaserad teknik, för första gången i det mid-infraröda frekvensområdet. Det befanns att spektrometern var känslig, snabb, robust och kapabel till multiämnesdetektion med en detektionsgräns på 2 ppb för CH4 för korta mättider (25 ms).
37
Edlund, Adam. "Implementation of continuous filtering frequency comb Vernier spectroscopy for continuous acquisition of spectra in a flame." Thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-142426.
Full textAbstract:
In this project laser absorption spectroscopy was performed on a flame in a Fabry-Pérot cavity, using an optical frequency comb. Optical frequency comb spectroscopy is a technique that allows broadband ultra-sensitive detection of molecular species in gas phase. Optical frequency combs are generated by femtosecond mode-locked lasers, which generate short pulses and whose spectrum consists of a comb of sharp laser lines covering a broad spectral range. Doing spectroscopy with optical frequency combs can hence be compared to measurements with thousand of synchronised continuous wave lasers simultaneously, which enables broadband sensitive measurements in short acquisition times. A Vernier spectrometer uses the filtering ability of the cavity to allow sequential transmission of parts of the frequency comb spectrum. Its technical simplicity and robustness make it a good candidate for measuring in turbulent environments. The aim of the project was to implement continuous-filtering Vernier spectroscopy in a setup for measuring absorption spectra in air and in a flame. This was done by using an Er:fiber femtosecond laser emitting in the near-infrared wavelength range and a Fabry-Pérot cavity containing the flame. The cavity, which consists of two highly reflective mirrors, lets the light of the comb interact with the molecules in the flame for each of the many round-trips it perform; thus increasing the sensitivity to absorption. An active locking mechanism was implemented to stabilize the coupling of the optical frequency comb to the cavity. The locking allowed multiple measurements to be averaged which reduced noise. A galvanometer scanner was added to the system which was used to measure a broad part of the comb spectrum. Hot water absorption lines were detected in the swept comb spectrum and a candidate absorption peak for OH absorption was recorded. The spectrometer today has opportunities for improvements. A frequency calibration should be implemented which is essential for making estimates of reactant/product concentrations in combustion processes.
38
Lin, Rui. "High-capacity short-reach optical communications." Doctoral thesis, KTH, Kommunikationssystem, CoS, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-196580.
Full textAbstract:
The global traffic is experiencing an exponential growth posing severe challenges to the communication networks in terms of capacity. As a future-proof technology fiber communication is widely implemented in different network segments, which can be categorized by transmission distance as long-haul and short-reach. This thesis focuses on the short-reach communication networks including fiber access network connecting the end users to the metro/core networks that covering tens of kilometers and optical datacenter network handling the traffic within the datacenter with distance up to a few kilometers. For fiber access networks, wavelength division multiplexing passive optical networks (WDM-PONs) assign a dedicated wavelength channel to each user guaranteeing high data rate. Dense channels enlarges the user count but makes the signals vulnerable to the wavelength drift. In this regard we propose two schemes based on optical frequency comb technique to generate stable carriers for WDM-PONs. Meanwhile, radio-over-fiber techniques allows the transmission of radio signals between central offices and the cells. Millimeter wave (MMW) over fiber, on the other hand, offer high bandwidth for future high capacity mobile access. We propose and experimentally demonstrate a palm-shaped spectrum generation where the high-power central carrier can be used for upstream transmission while multiple MMW bands are capable of transmitting different downstream data simultaneously. Regarding optical datacenter networks, passive optical interconnects (POIs) have been proposed as an energy-efficient solution since only passive optical components are used for server interconnection. However, the high insertion loss may result in a scalability problem. We develop a methodology that considers various physical-layer aspects, e.g., receiver types, modulation formats, to quantify the scalability of POIs. Both theoretical analyses and experimental measurements have been performed to assess the scalability of various coupler-based POIs.Den globala datatrafiken växer exponentiellt, både på grund av nya bandbreddskrävande applikationer och ökningen av antalet användare. Detta innebär en utmaning för kommunikationsnätens kapacitet. Fiberoptisk kommunikation är en framtidssäker teknik för att möta detta kapacitetsbehov och används redan i stor utsträckning i olika delar av näten. Beroende på överföringsavstånd, kan fibernät kategoriseras som långdistansnät eller nät med kort räckvidd. Denna avhandling behandlar nät med kort räckvidd, innefattande dels 1) accessnät som förbinder slutanvändarna till stadsnätet/ huvudnätet och typiskt omfattar tiotals kilometer, dels 2) optiska datanätverk som hanterar den interna trafiken inom datacenter med överföringsavstånd upp till ett par kilometer.För fiberaccessnät är en av de lovande teknikerna våglängdsmultiplexade passiva optiska nät (WDM-PON), där en dedicerad våglängdskanal tilldelas varje användare vilket garanterar hög datahastighet. Genom ett litet kanalavstånd så kan antalet användare i WDM-PON utökas men det gör samtidigt systemet känsligt för våglängdsdrift hos lasrarna. För att råda bot på detta, föreslår vi två system baserade på optisk frekvenskams-teknik. Vi validerar experimentellt att de kan generera stabila optiska bärvågor för WDM-PON. Radio-över –fiber-tekniken gör samtidigt det möjligt att sända radiosignaler över en lång sträcka och används därför i mobilsystem för överföring mellan centralstationen och radiocellerna. Millimetervågor (MMW) över fiber erbjuder ännu större modulationsbandbredd och är lovande för framtidens mobilradiosystem med hög kapacitet. I denna avhandling föreslår vi, och demonstrerar experimentellt, generation av ett frekvenskams-spektrum som är format som en handflata, där en central bärare med hög effekt (långfingret på handflatan) kan användas i radiocellerna för uppströms överföring, medan multipla MMW band (övriga fingrar) samtidigt kan överföra olika data nedströms. När det gäller nätverk för optiska datacenter, har passiva optiska interconnects (POI) föreslagits som en energieffektiv lösning, där endast passiva optiska komponenter används för ihopkoppling av servrarna. Höga inkopplingsförluster hos passiva optiska komponenter kan emellertid leda till allvarliga skalbarhetsproblem. I denna avhandling presenterar vi en nyutvecklad metod för att kvantifiera skalbarheten, vilken tar hänsyn till olika faktorer i det fysiska lagret som t.ex. mottagartyp och modulationsformat. Både teoretiska analyser och experimentella mätningar har utförts för att utvärdera skalbarheten hos olika kopplarbaserade POI.
QC 20161117
39
Silander, Isak. "Cavity enhanced optical sensing." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-110278.
Full textAbstract:
An optical cavity comprises a set of mirrors between which light can be reflected a number of times. The selectivity and stability of optical cavities make them extremely useful as frequency references or discriminators. With light coupled into the cavity, a sample placed inside a cavity will experience a significantly increased interaction length. Hence, they can be used also as amplifiers for sensing purposes. In the field of laser spectroscopy, some of the most sensitive techniques are therefore built upon optical cavities. In this work optical cavities are used to measure properties of gas samples, i.e. absorption, dispersion, and refractivity, with unprecedented precision. The most sensitive detection technique of all, Doppler-broadened noise-immune cavity enhanced optical heterodyne molecular spectrometry (Db NICE-OHMS), has in this work been developed to an ultra-sensitive spectroscopic technique with unprecedented detection sensitivity. By identifying limiting factors, realizing new experimental setups, and determining optimal detection conditions, the sensitivity of the technique has been improved several orders of magnitude, from 8 × 10-11 to 9 × 10-14 cm-1. The pressure interval in which NICE-OHMS can be applied has been extended by derivation and verification of dispersions equations for so-called Dicke narrowing and speed dependent broadening effects. The theoretical description of NICE-OHMS has been expanded through the development of a formalism that can be applied to the situations when the cavity absorption cannot be considered to be small, which has expanded the dynamic range of the technique. In order to enable analysis of a large number of molecules at their most sensitive transitions (mainly their fundamental CH vibrational transitions) NICE-OHMS instrumentation has also been developed for measurements in the mid-infrared (MIR) region. While it has been difficult to realize this in the past due to a lack of optical modulators in the MIR range, the system has been based on an optical parametric oscillator, which can be modulated in the near-infrared (NIR) range. As the index of refraction can be related to density, it is possible to retrieve gas density from measurements of the index of refraction. Two such instrumentations have been realized. The first one is based on a laser locked to a measurement cavity whose frequency is measured by compassion with an optical frequency comb. The second one is based on two lasers locked to a dual-cavity (i.e. one reference and one measurement cavity). By these methods changes in gas density down to 1 × 10-9 kg/m3 can be detected. All instrumentations presented in this work have pushed forward the limits of what previously has been considered measurable. The knowledge acquired will be of great use for future ultrasensitive cavity-based detection methods.
40
Quinlan, Franklyn. "LOW NOISE, HIGH REPETITION RATE SEMICONDUCTOR-BASED MODE-LOCKED LASERS FOR SIGNAL PROCESSING AND COHERENT COMMUNICATIONS." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3393.
Full textAbstract:
This dissertation details work on high repetition rate semiconductor mode-locked lasers. The qualities of stable pulse trains and stable optical frequency content are the focus of the work performed. First, applications of such lasers are reviewed with particular attention to applications only realizable with laser performance such as presented in this dissertation. Sources of timing jitter are also reviewed, as are techniques by which the timing jitter of a 10 GHz optical pulse train may be measured. Experimental results begin with an exploration of the consequences on the timing and amplitude jitter of the phase noise of an RF source used for mode-locking. These results lead to an ultralow timing jitter source, with 30 fs of timing jitter (1 Hz to 5 GHz, extrapolated). The focus of the work then shifts to generating a stabilized optical frequency comb. The first technique to generating the frequency comb is through optical injection. It is shown that not only can injection locking stabilize a mode-locked laser to the injection seed, but linewidth narrowing, timing jitter reduction and suppression of superfluous optical supermodes of a harmonically mode-locked laser also result. A scheme by which optical injection locking can be maintained long term is also proposed. Results on using an intracavity etalon for supermode suppression and optical frequency stabilization then follow. An etalon-based actively mode-locked laser is shown to have a timing jitter of only 20 fs (1Hz-5 GHz, extrapolated), optical linewidths below 10 kHz and optical frequency instabilities less than 400 kHz. By adding dispersion compensating fiber, the optical spectrum was broadened to 2 THz and 800 fs duration pulses were obtained. By using the etalon-based actively mode-locked laser as a basis, a completely self-contained frequency stabilized coupled optoelectronic oscillator was built and characterized. By simultaneously stabilizing the optical frequencies and the pulse repetition rate to the etalon, a 10 GHz comb source centered at 1550 nm was realized. This system maintains the high quality performance of the actively mode-locked laser while significantly reducing the size weight and power consumption of the system. This system also has the potential for outperforming the actively mode-locked laser by increasing the finesse and stability of the intracavity etalon. The final chapter of this dissertation outlines the future work on the etalon-based coupled optoelectronic oscillator, including the incorporation of a higher finesse, more stable etalon and active phase noise suppression of the RF signal. Two appendices give details on phase noise measurements that incorporate carrier suppression and the noise model for the coupled optoelectronic oscillator.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
41
Muñoz-Arcos, Christian Daniel. "Optical Microwave Signal Generation for Data Transmission in Optical Networks." Thesis, Toulouse, ISAE, 2020. http://www.theses.fr/2020ESAE0013.
Full textAbstract:
La croissance des services de télécommunications et l’augmentation du trafic de données àl’échelle mondiale favorise le développement et l’intégration de différents réseaux de transmissionde données. Un exemple de ce développement est constitué par les réseaux defibres optiques, qui sont actuellement chargés d’interconnecter les continents par des liaisonslongues avec des taux de transfert importants. Les réseaux optiques, ainsi que les réseauxsupportés par d’autres moyens de transmission, utilisent des signaux électriques à certainesfréquences pour la synchronisation des éléments du réseau. La qualité de ces signaux est unfacteur décisif dans la performance globale du système, c’est pourquoi leur bruit de phasedoit ˆetre aussi faible que possible.Ce document décrit la conception et la mise en œuvre d’un système optoélectronique pour lagénération de signaux micro-ondes à l’aide de diodes laser à cavité verticale (VCSEL) et sonintégration dans un système de transmission optique de données. Compte tenu du fait que lesystème proposé intègre un laser VCSEL directement modulé, une caractérisation théoriqueet expérimentale a été élaborée sur la base des équations d’évolution du laser, de mesuresdynamiques et statiques, et d’un modèle électrique équivalent de la région active. Cetteméthode a permis l’extraction de certains paramètres intrinsèques du VCSEL, ainsi que lavalidation et la simulation de ses performances dans différentes conditions de modulation.Le VCSEL utilisé émet en bande C et a été sélectionné en considérant que cette bande estcouramment utilisée dans les liaisons à longue distance.Le système proposé est constitué d’une boucle fermée qui déclenche l’oscillation grâce auxsources de bruit des composants et module le VCSEL en fort signal pour générer des impulsionsoptiques (gain switching). Ces impulsions optiques, qui dans le domaine des fréquencescorrespondent à un peigne de fréquences optiques, sont détectées pour générer simultanémentune fréquence fondamentale (déterminée par un filtre passe-bande) et plusieurs harmoniques.Le bruit de phase mesuré à10 kHz de la porteuse à1,25 GHz est de -127,8 dBc/Hz, etconstitue la valeur la plus faible signalée dans la littérature pour cette fréquence et cette architecture.La gigue et la largeur d’impulsion optique ont été déterminées lorsque différentescavités résonantes et différents courants de polarisation étaient utilisés. La durée d’impulsionThe massive growth of telecommunication services and the increasing global data traffic boostthe development, implementation, and integration of different networks for data transmission.An example of this development is the optical fiber networks, responsible today for theinter-continental connection through long-distance links and high transfer rates. The opticalnetworks, as well as the networks supported by other transmission media, use electricalsignals at specific frequencies for the synchronization of the network elements. The qualityof these signals is usually determined in terms of phase noise. Due to the major impact ofthe phase noise over the system performance, its value should be minimized.The research work presented in this document describes the design and implementation ofan optoelectronic system for the microwave signal generation using a vertical-cavity surfaceemittinglaser (VCSEL) and its integration into an optical data transmission system. Consideringthat the proposed system incorporates a directly modulated VCSEL, a theoreticaland experimental characterization was developed based on the laser rate equations, dynamicand static measurements, and an equivalent electrical model of the active region. This proceduremade possible the extraction of some VCSEL intrinsic parameters, as well as thevalidation and simulation of the VCSEL performance under specific modulation conditions.The VCSEL emits in C-band, this wavelength was selected because it is used in long-haullinks. The proposed system is a self-initiated oscillation system caused by internal noise sources,which includes a VCSEL modulated in large signal to generate optical pulses (gain switching).The optical pulses, and the optical frequency comb associated, generate in electricaldomain simultaneously a fundamental frequency (determined by a band-pass filter) and severalharmonics. The phase noise measured at 10 kHz from the carrier at 1.25 GHz was -127.8dBc/Hz, and it is the lowest value reported in the literature for this frequency and architecture.Both the jitter and optical pulse width were determined when different resonantcavities and polarization currents were employed. The lowest pulse duration was 85 ps andwas achieved when the fundamental frequency was 2.5 GHz. As for the optical frequencycomb, it was demonstrated that its flatness depends on the electrical modulation conditions.The flattest profiles are obtained when the fundamental frequency is higher than the VCSELrelaxation frequency. Both the electrical and the optical output of the system were integrated into an optical transmitter.The electrical signal provides the synchronization of the data generating equipment,whereas the optical pulses are employed as an optical carrier. Data transmissions at 155.52Mb/s, 622.08 Mb/s and 1.25 Gb/s were experimentally validated. It was demonstrated thatthe fundamental frequency and harmonics could be extracted from the optical data signaltransmitted by a band-pass filter. It was also experimentally proved that the pulsed returnto-zero (RZ) transmitter at 1.25 Gb/s, achieves bit error rates (BER) lower than 10−9 whenthe optical power at the receiver is higher than -33 dBm. la plus faible, 85 ps, a été obtenue lorsque la fréquence fondamentale du système était de 2,5 GHz. En ce qui concerne le peigne de fréquences optiques, il a été démontré que la formedu peigne dépend des conditions de modulation électrique et que les profils les plus platssont obtenus lorsque la fréquence fondamentale est supérieure à la fréquence de relaxationdu VCSEL. Les sorties électrique et optique du système ont été intégrées dans un émetteur optique. Lesignal électrique permet la synchronisation de l’équipement responsable de la génération desdonnées, tandis que les impulsions optiques sont utilisées comme porteuse optique. La transmissionde données à 155,52 Mb/s, 622,08 Mb/s et 1,25 Gb/s a été validée expérimentalement
42
Kovalchuk, Evgeny. "Optical parametric oscillators for precision IR spectroscopy and metrology." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15759.
Full textAbstract:
In der vorliegenden Doktorarbeit wird ein Dauerstrich Optisch Parametrischer Oszillator (cw OPO) vorgestellt, der speziell für die hochauflösende Dopplerfreie Molekülspektroskopie und Metrologie entwickelt wurde. Der kontrollierte Zugang zu jeder beliebigen Wellenlänge im breiten Emissionsspektrum von OPOs wie auch das präzise Abstimmen seiner Ausgangsfrequenz über zu untersuchende molekulare und atomare Übergänge stellten lange Zeit Probleme dar, deren Lösung die Grundzielsetzung dieser Arbeit war. Das im Laufe dieser Arbeit entwickelte System hat diese Ziele vollständig erreicht, was durch verschiedene Messungen und Anwendungen demonstriert wurde. Zu diesem Zweck wurde ein neues OPO-Design mit einem Intracavity-Etalon entwickelt und aufgebaut, wobei der OPO auf dem Konzept eines einfach-resonanten cw OPOs mit resonanter Pumpwelle basiert. Die OPO-Ausgangsstrahlung zeigt sehr gute Langzeitstabilität und Spektraleigenschaften, welche durch direkte Frequenzvergleichsmessungen mit einem optischen Methan-Frequenzstandard im Infraroten bestimmt wurden. Eine Idler-Linienbreite von 12 kHz und ein Modensprung-freier Betrieb des OPOs über einen Zeitraum von einigen Tagen wurde beobachtet. Außerdem wurde gezeigt, dass ein OPO zu einer hochstabilen optischen Referenz phasengelockt und somit seine Frequenz sehr genau kontrolliert und durchgestimmt werden kann. Als erste erfolgreiche Anwendung eines OPOs in der Dopplerfreien Spektroskopie wurde ein Aufbau zur Frequenz-Modulationsspektroskopie in Methan realisiert. Weiterhin, wurde der entwickelte cw OPO mit einem femtosekunden optischen Frequenzkamm kombiniert, um eine neue Idee für eine kohärente Verbindung zwischen dem sichtbaren und dem infraroten Spektralbereich zu realisieren. Als erste Demonstration dieser Technologie wurde ein direkter absoluter Frequenzvergleich zwischen einem Jod-stabilisierten Laser bei 532 nm und einem Methan-stabilisierten Laser bei 3390 nm durchgeführt.This thesis presents a continuous-wave optical parametric oscillator (cw OPO), specially developed for high-resolution Doppler-free molecular spectroscopy and metrology. The basic objective was to solve the long-standing problem of controlled access to any desired wavelength in the wide emission range of OPOs, including the ability to precisely tune the output frequency over the molecular and atomic transitions of interest. The system implemented during this work fully achieves these goals and its performance was demonstrated in various measurements and applications. For this aim, a new design for the OPO cavity with an intracavity etalon was implemented, extending the concept of a cw singly resonant OPO with resonated pump wave. The newly developed device demonstrates very good long-term stability and spectral properties, which were determined in direct beat frequency measurements with a methane infrared optical frequency standard. Thus, an idler radiation linewidth of 12 kHz and mode-hop-free operation of the OPO over several days were observed. Furthermore, it was shown that an OPO can be phase locked to a highly stable optical reference and thus much more precisely controlled and tuned. As the first successful application of OPOs in Doppler-free spectroscopy, a frequency modulation spectroscopy setup for detection of sub-Doppler resonances in methane was implemented. Furthermore, the developed cw OPO was integrated with a femtosecond optical frequency comb to realize a new concept for a coherent link between the visible and infrared spectral ranges. As a first demonstration of this technique, a direct absolute frequency comparison between an iodine stabilized laser at 532 nm and a methane stabilized laser at 3390 nm was performed.
43
Saquinaula, Brito José Luis 1981. "Pentes de frequências ópticas baseados em moduladores eletro-ópticos e fibras altamente não lineares." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276926.
Full textAbstract:
Orientadores: Flávio Caldas da Cruz, Paulo Clóvis Dainese JúniorDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
Made available in DSpace on 2018-08-28T22:50:49Z (GMT). No. of bitstreams: 1 SaquinaulaBrito_JoseLuis_M.pdf: 4387885 bytes, checksum: 7b7c41672acbabf5abc5b7c398df00c0 (MD5) Previous issue date: 2015
Resumo: Nos últimos 15 anos os pentes de frequências ópticas baseados em lasers de femtossegundos representaram uma revolução na área de metrología e medidas de precisão, permitindo medir diretamente frequências de várias centenas de THz assim como posibilitando o advento de relógios atômicos ópticos. Estes pentes também têm encontrado importantes aplicações em outras áreas da Física, tais como espectroscopia de alta resolução e precisão, geração de altos harmônicos na região da ultravioleta e raios X moles, ou até na procura de exoplanetas através da calibração de espectrômetros astrofísicos. Neste trabalho, estudamos a geração de pentes de frequências ópticas baseados em moduladores eletro-ópticos e fibras altamente não lineares, com o objetivo de implementar novas configurações, alternativas aos pentes baseados em lasers de femtossegundos. Um objetivo é implementar pentes com a maior largura de banda possível que ao mesmo tempo preservem alta coerência entre as frequências geradas, aproveitando componentes comercialmente disponíveis, desenvolvidos para comunicações ópticas na região espectral de 1550 nm. Buscamos implementar dois tipos de pentes de frequências ópticas. Um deles usa um modulador eletro-óptico e gera um pente com pequena largura de banda (10 nm) e espaçamento entre frequências de 25 GHz. O outro pente, gerado com base em fenômenos não lineares em fibras ópticas, fornece maior largura de banda (270 nm) com espaçamento entre frequências de 776 GHz. No caso do pente de frequências gerado pelo modulador (pente eletro-óptico), o processo é devido ao fenômeno eletro-óptico (efeito Pockels) dentro de um cristal de Niobato de Lítio que também forma uma cavidade óptica ressonante. Utilizamos um laser semicondutor contínuo e de frequência única em 1550 nm para gerar um pente (eletro-óptico) com largura espectral de 10 nm com espaçamento de 25 GHz entre as frequências. O outro pente de frequências ópticas é baseado na criação em cascata de produtos da mistura de quatro ondas produzidos a partir de dois lasers semicondutores contínuos, que foram utilizados tanto em onda contínua (cw) ou pulsados, i.e., com modulação de amplitude. Obtivemos espectros com largura de 269 nm (1431 nm ¿ 1700 nm) e espaçamento entre linhas de 6.3 nm (776 GHz). Finalmente, foi alargado o espectro do pente de frequências ópticas gerado pelo modulador eletro-óptico ao usar fibras altamente não lineares. O espectro obtido apresentaram um alargamento modesto, com largura de 23 nm e separação de 25 GHz entre as frequências
Abstract: In the last 15 years, optical frequency combs based on femtosecond lasers have represented a revolution in the area of metrology and precision measurements, making it possible to directly measure frequencies of several hundred terahertz, and affording the advent of optical atomic clocks. These frequency combs today are used in important applications in other areas of Physics, such as high resolution and accuracy spectroscopy, generation of high harmonics in the ultraviolet and soft X-rays region, or even in the search of exoplanets through calibration of Astrophysics spectrometers. In this work, we study the generation of optical frequency combs based on electro-optic modulators and highly nonlinear fibers, with the goal of implementing new configurations, which can be alternative to frequency combs based on femtosecond lasers. One particular goal is to implement frequency combs with the largest possible bandwidth, while still preserving the coherence between the generated frequencies, and taking advantage of commercially available components developed for optical communications, in the 1550 nm spectral region. We were interested in implement two types of optical frequency combs. One of them uses an electro-optical modulator and generates a frequency comb with small bandwidth (10 nm) and 25 GHz frequency spacing. The other comb, generated by nonlinear phenomena in optical fibers, provides greater bandwidth (270 nm) with a frequency spacing of 776 GHz. In the case of the frequency comb generated by the modulator (electro-optical comb), the process is due to the electro-optical phenomenon (Pockels effect) within a Lithium Niobate crystal which also forms a resonant optical cavity. We use a continuous-wave, single frequency semiconductor laser at 1550 nm to generate a frequency comb with a spectral width of 10 nm and 25 GHz frequency spacing. The other optical frequency comb is based on the creation of cascaded four-wave mixing products, produced from two continuous semiconductor lasers that were used both in continuous-wave (cw) or pulsed operation, i.e., with amplitude modulation.We obtained spectra with a width of 269 nm (1431 nm - 1700 nm) and line spacing of 6.3 nm (776 GHz). Finally, we combined both combs by using the highly nonlinear fiber to expand the optical comb spectrum generated by the electro-optical modulator. The resulting spectra showed a modest broadening, with a width of 23 nm and 25 GHz separation between frequencies
Mestrado
Física
Mestre em Física
1186840
134295/2013-7
CAPES
CNPQ
44
Tran, Dang Bao An. "Widely tunable and SI-traceable frequency-comb-stabilised mid-infrared quantum cascade laser : application to high precision spectroscopic measurements of polyatomic molecules." Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCD060.
Full textAbstract:
Ce manuscrit présente le développement d’un spectromètre dans le moyen infra-rouge qui combine très haute résolution, accordabilité, sensibilité de détection et contrôle de la fréquence absolue. Un laser à cascade quantique (QCL) émettant à 10.3 μm est asservi en phase sur un peigne de fréquences optique lui-même stabilisé sur un laser ultrastable à 1.55 μm transmis par lien optique fibré à partir du LNE-SYRTE, où cette référence de fréquence est contrôlée par rapport aux étalons primaires. On obtient ainsi un QCL de largeur ~ 0.1 Hz, avec une stabilité meilleure que 10⁻¹⁵ à 1 s, et une incertitude de 4 × 10⁻¹⁴ sur sa fréquence absolue. De plus, le QCL peut être balayé largement sur 1.4 GHz sans dégradation de la stabilité et du contrôle absolu de la fréquence. Ce QCL a permis de sonder plusieurs molécules par absorption saturée dans une cellule multipassage. Nous avons démontré une incertitude statistique sur la mesure des fréquences d’absorption au niveau du kHz et une incertitude systématique inférieure à 10 kHz. Nous avons enregistré de nombreuses raies du méthanol, dont plusieurs doublets et des raies très peu intenses, dont certaines n’avaient jamais été observées. La mesure de quelques dizaines de raies du trioxane nous a permis d’en déterminer les paramètres spectroscopiques avec précision. Nous avons également enregistré la structure hyperfine d’une raie de l’ammoniac jusqu’ici non résolue. Ce dispositif est essentiel pour le projet en cours au LPL d’observer la violation de parité dans les molécules. Il permettra également de nombreuses applications de la physique atmosphérique ou interstellaire aux tests de physique fondamentale au-delà du modèle standardThe thesis consists in developing a high-resolution mid-infrared spectrometer traceable to primary frequency standards and providing a unique combination of resolution, tunability, detection sensitivity and frequency control. A quantum cascade laser (QCL) emitting at 10.3 µm is phase locked to an optical frequency comb stabilized to a remote 1.55 µm ultra-stable reference developed at LNE-SYRTE, monitored against primary frequency standards and transferred to LPL via an active noise compensated fibre link. This results in a 0.1 Hz QCL linewidth, a stability below 10⁻¹⁵ at 1 s and an uncertainty on its absolute frequency below 4 × 10⁻¹⁴. Moreover, the setup allows the QCL to be widely scanned over 1.4 GHz while maintaining the highest stabilities and precision. This QCL was used to carry out saturated absorption spectroscopy of several molecules in a compact multipass cell. We demonstrated statistical uncertaintyon line-center frequencies at the kHz level and sub-10 kHz systematic uncertainty. We have recorded several singular K-doublets and many rovibrational transitions of methanol, in particular weak transitions and weak doublets - unreported so far. Precise parameters modelling trioxaneh ave been determined with only a few tens of rovibrational transitions recorded at unprecedented accuracy. The quadrupole hyperfine structure of an ammonia transition has been resolved for thefirst time. This setup constitutes a key element for the project aiming at the first observation of parity violation in molecules currently held at LPL, and, more generally, for various fields of physics, from atmospheric and interstellar physics to fundamental physics beyond the standard model
45
Silva, Rui Miguel Horta Coelho da. "WDM-PON architecture with centralized generation of optical multi-carriers." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14571.
Full textAbstract:
Mestrado em Engenharia Eletrónica e TelecomunicaçõesThe rapid growth of the telecommunications area and the increasing demand for bandwidth by users has led to the need of develop the Wavelength-division multiplexed passive optical network (WDM-PON) architecture, which can increase the bandwidth of the existing network without the necessity of installing new fiber . A key technique for the high capacity WDM-PON networks is the generation of optical multi-carriers. This technique is the main focus point of this dissertation, which begins to look at the generation of optical multi-carriers in a general way and then will try to find the best way to apply this technique to an Ultra Dense WDM-PON (UDWDM-PON) application. Two distinct methods of generating optical multi-carriers were tested and it was concluded that the ‘single stage dual arm driven MZM’ is the one that offers more benefits to an UDWDM-PON application.
O rápido crescimento do setor das telecomunicações e a crescente procura de largura de banda por parte dos utilizadores, levou à necessidade de desenvolvimento da arquitetura wavelength-division multiplexed passive optical network (WDM-PON), que permite aumentar a largura de banda da rede existente sem a necessidade de instalar nova fibra. Uma técnica chave para a criação de redes WDM-PON de alta capacidade é a geração de multi-portadoras óticas. Esta técnica é o principal foco desta dissertação, que começa por olhar para a geração de multi-portadoras óticas de uma forma geral e de seguida vai encontrar a melhor forma para aplicar esta técnica a uma aplicação Ultra Dense WDM-PON (UDWDM-PON). Dois métodos distintos de gerar multi-portadoras foram testadas e foi concluído que o ‘single stage dual arm driven MZM’ é o método que mais benefícios apresenta para uma aplicação UDWDM-PON.
46
Konečný, Aleš. "Časoprostorová dynamika a koherentní řízení frekvenčních hřebenů kvantových kaskádových laserů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443759.
Full textAbstract:
Kvantové kaskádové laserové frekvenční hřebeny jsou slibnými kandidáty pro nové miniaturizované spektrometry bez pohyblivých částí. Mohou být generovány v samočinném režimu pomocí různých nelinearit vyvolaných asymetrickým ziskem a vlnovodovou disperzí. K simulaci samočinných hřebenů byl použit dostupný vysoce optimalizovaný nástroj založený na modelu postupné vlny. Dále byl rozšířen o funkci zamykání optickým vstřikováním, koherentní techniky ovládání frekvenčních hřebenů. Následné simulace potvrdily uzamčení pomocí vstřikovaného signálu. Bylo zjištěno, že disperze grupové rychlosti (GVD) má významný dopad na rozsah zamykání. GVD byla vypočtena pro typické zařízení a frekvenční hřeben byl uzamčen pomocí optického vstřikování v rozsahu ladění od -2 do 47 MHz.
47
Deroh, Koffi. "Interactions Brillouin et Kerr dans de nouvelles fibres optiques adaptées à des applications dans l'infrarouge proche et moyen." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD053.
Full textAbstract:
Durant la dernière décennie, on constate une forte évolution de la couverture spectrale des sources lasers cohérentes compactes vers l’infrarouge moyen, notamment pour des applications de spectroscopie et de bio-photonique. Cette thèse s’inscrit dans ce développement par l’étude de fibres optiques spéciales conçues spécialement pour une transition entre les gammes spectrales du proche infrarouge et de l’infrarouge moyen, plus particulièrement pour les longueurs d’ondes autour de 2 µm. Ces fibres en verres de tellurites ou de silice fortement dopée à l’oxyde de germanium présentent des caractéristiques non-linéaires avantageuses pour le développement de systèmes lasers ou de conversion de fréquences, en utilisant les processus de diffusion Brillouin et d’effet Kerr. Nos mesures expérimentales révèlent une efficacité Brillouin bien meilleure (jusqu’à 67 fois supérieure) que dans une fibre standard des télécommunications optiques. Nous démontrons la possibilité de développer des lasers Brillouin à fibre optique avec des largeurs de raie spectrale et des seuils de l’ordre de quelques dizaines de kilohertz et centaines de mW, respectivement. Ces cavités lasers Brillouin peuvent aussi générer des peignes de fréquences optiques par mélanges à quatre-ondes multiples. Ces sources spectrales hybrides de type Brillouin-Kerr ont la particularité d’être symétriques, stables et accordables en fréquence. Enfin, les fibres optiques en silice fortement dopée présentent une sensibilité réduite de la fréquence caractéristique Brillouin aux contraintes mécanique et en température. En effet, un fort dopage à 98 mol % permet d’obtenir une fréquence élastique insensible à la température aux longueurs d’ondes de 1,55 et 2 µm. Ce pouvoir athermique se révèle fondamental pour la discrimination des effets de température et de contrainte mécanique dans le domaine des capteurs à fibre optiqueDuring the last decade, it is worth to mention the significant evolution of the spectral coverage of compact coherent laser sources towards the mid-infrared, in particular stimulated by spectroscopy and bio-photonic applications. The present thesis is part of this development through the investigation of specialty optical fibers designed to bridge the gap between the near-infrared and mid-infrared regions, especially for wavelengths around 2 μm. These fibers based on tellurite glasses or heavily germanium-doped silica fibers exhibit advantageous nonlinear characteristics for the development of laser systems or frequency conversion devices, by using the stimulated Brillouin scattering and Kerr effect. Our experimental measurements reveal a significant increase of Brillouin efficiency (up to 67 times higher) when compared to standard telecom silica fibers. We demonstrate the possibility of developing Brillouin fiber lasers with linewidths and thresholds about few tens of kilohertz and hundreds of mW, respectively. Such Brillouin laser cavities can also generate optical frequency combs by multiple four-wave mixing. The resulting spectral sources are shown to be symmetrical, stable and frequency-tunable. Finally, we show that the highly doped silica fibers have the distinctive feature of reduced sensitivity of the Brillouin shift to the mechanical tensile strain and temperature. In particular, the high 98 mol % doping level makes possible to obtain a temperature-insensitive elastic frequency at wavelengths of 1.55 and 2 μm. This athermal behavior is fundamental to discriminate the effects of temperature and mechanical strain in the field of fiber sensors
48
Baillot, Maxime. "Mélange à quatre ondes multiple pour le traitement tout-optique du signal dans les fibres optiques non linéaires." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S068/document.
Full textAbstract:
Le mélange à quatre ondes est un effet non linéaire sensible à la phase qui suscite de nombreux intérêts dans le domaine de la génération de peignes de fréquences et du traitement tout optique du signal par exemple. Un peigne de fréquences peut en effet s'obtenir par effet de mélange à quatre ondes 1en cascade. Dans ce cas, un nombre N d'ondes interagissent entre elles via l'effet Kerr et la modélisation d'un tel processus doit tenir compte de tous les couplages possibles entre les ondes. Au cours de mes travaux de thèse, je me suis intéressé, dans un premier temps, à la modélisation du mélange à quatre ondes dit multiple pour lequel un nombre quelconque N d'ondes interagissent entre elles. J'ai proposé une formulation générale permettant d'identifier simplement tous les termes de mélange à quatre ondes issus de toutes les combinaisons possibles de couplage entre les ondes et leur désaccord de phase associé. J'ai validé cette approche en proposant une étude théorique et expérimentale d'un processus de mélange à quatre ondes multiple dans une fibre optique non linéaire. Dans une deuxième partie, j'ai proposé, grâce au modèle élaboré précédemment, une étude théorique du phénomène de conversion de fréquence sensible à la phase, permettant la décomposition des composantes en quadrature d'un signal optique. Dans la littérature, cette expérience fut démontrée initialement avec quatre ondes pompes et dans plusieurs types de composants non linéaires. J'ai pu démontrer, au cours de mes travaux, que trois pompes étaient suffisantes pour réaliser l'expérience et j'ai déterminé des relations analytiques simples permettant de choisir les paramètres expérimentaux (notamment l'amplitude et la phase des pompes) rendant possible la décomposition des composantes en quadrature d'un signal. J'ai validé cette étude par la démonstration expérimentale d'un convertisseur de fréquence sensible à la phase avec uniquement trois pompes et j'ai étudié théoriquement les effets de la dispersion chromatique sur les performances du convertisseur de fréquence. Enfin, dans une dernière partie, j'ai caractérisé des fibres optiques microstructurées en verre de chalcogénure fabriquées dans le cadre d'une collaboration avec Perfos, l'Institut des Sciences Chimiques de Rennes et SelenOptics. Dans ce cadre, j'ai mis en place un banc de mesure de la dispersion chromatique et du coefficient non linéaire des fibres optiques basé sur le mélange à quatre ondesFour-wave mixing is a phase-sensitive nonlinear effect that arouses interest, particularly in the fields of frequency comb generation and all-optical signal processing. As an example, frequency combs can be produced thanks to a cascaded four-wave mixing process. In this case, N waves can interact with each other through the optical Kerr effect, and one has to take into account all the possible interactions to be able to adequately model the process. During my PhD thesis, I was interested in modeling the so-called multiple four-wave mixing process, in which any number N of waves can interact with each other. I proposed a general formulation that allows to easily identify all the four-wave mixing terms originating from all the possible combinations of wave coupling and their associated phase-mismatch terms. I validated this approach through the theoretical and experimental study of a multiple four-wave mixing process in a nonlinear optical fiber. Thanks to the developed model, I then proposed a theoretical study of the phase-sensitive frequency conversion process, which permits to demultiplex the quadrature components of an optical signal. In the literature, this process was first experimentally demonstrated in several nonlinear devices using four pump waves. I demonstrated that only three pump waves were required to successfully perform the experiment, and I determined the simple analytical relations from which the adequate experimental parameters (namely, the amplitudes and phases of the pump waves) could be deduced. I finally validated this study by experimentally demonstrating a phase-sensitive frequency conversion process with only three pump waves, and I theoretically studied the influence of chromatic dispersion on the performance of this frequency converter. Finally, I characterized some chalcogenide microstructured optical fibers that were fabricated in the framework of a collaboration with Perfos, the Institut des Sciences Chimiques de Rennes, and SelenOptics. I set up a test bench based on the four-wave mixing process in order to measure the chromatic dispersion and nonlinear coefficient of some optical fibers
49
Abd, Alrahman Chadi. "Spectroscopie Laser avec des cavités résonantes de haute finesse couplées à un peigne de fréquences : ML-CEAS et vernier effet techniques. Applications à la mesure in situ de molécules réactives dans les domaines UV et visible." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENY095/document.
Full textAbstract:
La communauté de la chimie atmosphérique souffre d'un manque de mesures rapides, fiables résolues spatialement et temporellement pour un large éventail de molécules réactives (radicaux tels que NO2, OH, BrO, IO, etc). En raison de leur forte réactivité, ces molécules contrôlent largement la durée de vie et la concentration de nombreuses espèces clés dans l'atmosphère, et peuvent avoir un impact important sur le climat. Les concentrations de ces radicaux sont extrêmement faibles (ppbv ou moins) et très variable dans le temps et dans l'espace, ce qui impose un véritable défi lors de la détection. Dans la première partie de cette thèse, un spectromètre UV robuste, compacte et transportable est développé, exploitant la technique ML-CEAS pour mesurer à des niveaux très faibles (pptv et même en dessous) des molécules réactives d'importance atmosphérique, en particulier, les radicaux d'oxyde d'halogènes, afin de répondre aux besoins émergents. La technique ML-CEAS est basée sur le couplage d'un laser femtoseconde à blocage de modes à une cavité optique de haute finesse, qui agit comme un piège à photons pour augmenter l'interaction entre la lumière et l'échantillon de gaz intracavité. Cela permet d'améliorer fortement la sensibilité d'absorption. La limite de détection obtenue pour le radical IO est de 20 ppqv pour un temps d'acquisition de 5 minutes, ce qui est un résultat impressionnant. Dans la deuxième partie de cette thèse, une nouvelle technique spectroscopique est développée appelée effet Vernier, qui est également basé sur l'interaction entre un laser femtoseconde à blocage de mode et une cavité optique de haute finesse. Cette technique fournit une sensibilité de détection similaire à la technique ML-CEAS, mais l'avantage est que le nombre des éléments spectraux est donné par la finesse de la cavité optique et donc peut atteindre plusieurs dizaines de milliers. De plus, cette configuration simplifie le montage expérimental par la suppression du spectrographe qui est remplacé par une simple photodiode. Le temps d'acquisition d'un spectre peut être aussi réduit à moins d' 1 msThe atmospheric chemistry community suffers a lack of fast, reliable and space resolved measurements for a wide set of reactive molecules (e.g. radicals such as OH, NO3, BrO, IO, etc). Due to their high reactivity, these molecules largely control the lifetime and concentration of numerous key atmospheric species, and may have an important impact on the climate. The concentrations of such radicals are extremely low (ppbv or less) and highly variable in time and space, which imposes a real challenge during the detection. In the first part of this thesis, a compact, robust and transportable UV spectrometer is developed, exploiting the Mode-Locked Cavity Enhanced Absorption Spectroscopy (ML-CEAS) technique to measure pptv and sub-pptv levels of atmospherically important reactive molecules, in particular, halogen oxide radicals, to respond to the emerging needs. The ML-CEAS technique is based on coupling a Mode-Locked femtosecond laser to a high finesse optical cavity, which acts as a photon trap to increase the interaction between the light and the intracavity gas sample, which highly enhances the absorption sensitivity. The detection limit obtained for the IO radical is 20 ppqv (part per quadrillion), which is an impressive result. In the second part of this thesis, a new spectroscopic technique is developed, called Vernier effect, which is also based on the interaction between a mode-locked femtosecond laser with a high finesse optical cavity. This technique provides detection sensitivity similar to that of ML-CEAS technique, but the advantage is that the number of the spectral elements is given by the cavity finesse, so it can reach ten thousands, as well as this technique has a simple setup, where the spectrograph is replaced by a photodiode. Additionally, the time required to measure one output absorption spectrum can be less than 1 ms
50
Collombon, Mathieu. "Résonance noire à trois photons sur un nuage d'ions calcium confinés." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0017.
Full textAbstract:
Les travaux présentés dans cette thèse décrivent l’ensemble de la démarche expérimentale qui a été mise en place afin d’observer un piégeage cohérent de population à trois photons sur un nuage d’ions calcium confinés en piège radio-fréquence. La réalisation d’un tel processus cohérent repose sur des contraintes expérimentales fortes concernant la relation de phase entre les trois lasers impliqués dans le processus d’interrogation ainsi que sur leurs finesses spectrales. Notre approche est basée sur l’optimisation des performances d’un laser stabilisé à 411 THz (729 nm) pour atteindre une stabilité de fréquence relative inférieure à 10⁻¹⁴ à 1 s. Ces performances ont ensuite été transférées vers un peigne de fréquence optique. Le comportement de cet instrument ainsi que les performances du transfert sont présentés dans ces travaux. Le peigne est alors utilisé comme oscillateur de transfert pour asservir les deux autres lasers impliqués dans l’interrogation des ions (866 nm et 794 nm). Grâce à ce travail sur la mise en relation des trois sources laser, ainsi que l’optimisation de leur qualités spectrales nous avons pu observer les premières résonances noires à trois photons dans le spectre de fluorescence des ions 40 Ca⁺. Ces résultats originaux ainsi que les premières études systématiques du comportement de la résonance en fonction de différents paramètres expérimentaux sont présentés. L’analyse de ces résultats a permis de définir clairement les conditions expérimentales à respecter pour une potentielle utilisation métrologique de cette résonance qui émane d’une superposition cohérente d’état stable ou métastableThe work presented in this thesis describes the complete experimental set-up and approach to realize three-photon coherent population trapping in a cloud of radiofrequency confined calcium ions. The realization of such a population trapping relies on a stringent conditions of the phase relationship between the three lasers involved in the interrogation process, and also their spectral linewidths. Our experimental approach is based on the optimization of the performance of a frequency-stabilized titanium-sapphirelaser at 411 THz (729nm) at the 10⁻¹⁴ level, in term of relative frequency uncertainties. This laser’s fre-quency stability is subsequently transfered to a optical frequency comb by means of a phase-locked loop. Then the two other lasers involved (866 nm and 794 nm) are phase-locked to the optical frequency combwith the same technique. This work describes the transfer method along with its measured performances. With all the three lasers sharing the same ultra-stable frequency reference we have been able to experi-mentally observe for the first time a 3-photon dark resonance in the fluorescence spectra of the 40 Ca⁺, signature of a coherent population trapping in a 3-photon scheme. The dependence of this resonance at experimental parameters, such as laser powers, laser detunings and local magnetic field, have been studied and are presented in this work. The preliminary results have allowed to explain the behaviour of the dark resonance and explored conditions for the use of the 3-photon dark line as a THz frequency standard