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Mukherjee, Shambo. "Development of a Fabry-Pérot optical interferometer with low thermal and accelerometric sensitivities". Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCD023.
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Cette thèse explore le développement d'un laser transportable à largeur de raie ultra fine intégrant une cavité Fabry-Pèrot de haute finesse. La cavité est fabriquée à partir d'un verre ULE à très faible expansion thermique avec des miroirs en silice fondue contactés optiquement, visant à minimiser les perturbations thermiques et mécaniques et à améliorer la stabilité de la fréquence. Une nouvelle méthode numérique de stabilisation de fréquence utilisant une plateforme FPGA est introduite, visant une stabilité relative de fréquence de 1e-15 à une seconde. Cette approche contraste avec les systèmes analogiques traditionnels en offrant une stabilité accrue et une complexité réduite. L'étude examine également plusieurs limitations des lasers ultra-stables comme le bruit de phase, le bruit thermique, etc. et plusieurs approches pour atténuer ces sources de bruit. En outre, un système de distribution de fréquences optiques utilisant des boucles à verrouillage de phase basé sur un FPGA et des liaisons par fibre optique est détaillé, garantissant une transmission stable du signal sur des distances de laboratoireThis thesis explores the development of a transportable, ultra-narrow linewidth laser integrating a high-finesse Fabry-Pèrot cavity made from ultra-low expansion glass with optically contacted Fused Silica mirrors, aiming to minimize thermal and mechanical perturbations and enhance frequency stability. A novel digital frequency stabilization method using an FPGA-based platform is introduced, targeting a fractional frequency stability of 1e-1 5 at 1-second integration. This approach contrasts traditional analog systems by offering increased stability and reduced complexity. The study also examines several limitations of ultra stable lasers like phase noise, thermal noise etc. and several approaches to mitigate these type of noise. Additionally, an optical frequency dissemination system using FPGA-based phaselocked loops and optical fiber links is detailed, ensuring stable signal transmission over laboratory distances
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Grobbelaar, Johannes Jacobus. "Phase noise measurement". Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6806.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011.ENGLISH ABSTRACT: The objective of the thesis is the development of a phase noise measuring system that makes use of crosscorrelation and averaging to measure below the system hardware noise floor. Various phase noise measurement techniques are considered after which the phase demodulation method is chosen to be implemented. The full development cycle of the hardware is discussed, as well as the post processing that is performed on the measured phase noise.
AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is die ontwikkeling van ’n faseruis meetstelsel wat gebruik maak van kruiskorrelasie en vergemiddeling om onder die ruisvloer van die meetstelsel se hardeware te meet. Verskeie faseruis meettegnieke word ondersoek en die fase demodulasie metode word gekies om geïmplementeer te word. Die volle ontwikkelingsiklus van die hardeware word bespreek, sowel as die naverwerking wat toegepas is op die gemete faseruis.
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Pham, Toan Thang. "Advances in opto-electronic oscillator operation for sensing and component characterization". Thesis, Cachan, Ecole normale supérieure, 2015. http://www.theses.fr/2015DENS0013/document.
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L'oscillateur optoélectronique (OEO) a été introduit pour la première fois en 1996 par S. Yao et L. Maleki, en tant qu'oscillateur microondes à très faible bruit de phase et obtenu par synthèse directe. Les développements de l'OEO concernent les applications en photonique microondes, télécommunications optiques, radar et traitement du signal. Mais l'OEO devrait aussi pouvoir être utilisé dans le domaine des capteurs. Dans cette thèse nous étudiants plusieurs aspects de l'OEO pour son application à la mesure d'indice de réfraction d'un liquide. Compte tenu de sa structure l'OEO dépend fortement des conditions ambiantes d'utilisation. S'il n'est pas bien optimisé ni contrôlé, il ne peut pas fonctionner correctement sur une longue durée. Nous avons étudié les influences de la température sur le modulateur électrooptique (EOM) et sur le comportement global de l'OEO. Un contrôle de température réduit de façon significative le phénomène de dérive de l'EOM. Afin de la supprimer complètement, nous avons mis au point une instrumentation construite autour d'une carte DSP, permettant de détecter et compenser la dérive du point de fonctionnement optique de l'EOM tout en contrôlant simultanément sa température. Une première technique est basée sur un signal de test, basse fréquence, appliqué à l'électrode DC du modulateur. Une deuxième solution consiste à travailler sur la puissance optique en sortie du modulateur. En combinant les deux on peut profiter des avantages de ces deux méthodes. Utilisant ainsi l'OEO nous avons testé plusieurs configurations pour mesurer l'indice de réfraction de quatre solutions chimiques bien connues, nous avons obtenu une variance de 3 pour mille. Les résultats sont en assez bon accord avec les publications correspondantes. Enfin nous avons aussi introduit une nouvelle méthode pour améliorer les mesures d'indice de réfraction faites à long terme en suivant, grâce à un analyseur vectoriel de réseau, les évolutions au cours du temps du temps de propagation dans la fibre optique. En introduisant à partir de cette mesure une correction aux mesures de la fréquence d'oscillation il est possible de réduire les fluctuations de cette fréquence à seulement 606 Hz, sur une durée de 62 h, ce que l'on peut comparer aux 8 GHz de l'oscillateur. Ainsi le rapport signal à bruit, peut être grandement amélioré lors de la mesure d'indice de réfraction et il doit être possible de diminuer la limite de détection des variations de l'indice de réfraction au cours du tempsThe optoelectronic oscillator (OEO) was first introduced in 1996 by S. Yao and L. Maleki as a very low phase noise microwave oscillator working in direct synthesis. The OEO developments concern applications in microwave photonics, optical telecommunication, radar and high speed signal processing systems but it should also be used in the sensing domain. In this thesis, we study several aspects to apply the OEO to liquid refractive index measurement. Because of its structure the OEO is very dependent on the ambient conditions. If the OEO is not optimized and controlled, it cannot operate well for long duration. We have analyzed the influences of temperature on the electrooptic modulator (EOM) and the global OEO behavior. Temperature control can significantly reduce the drift phenomena of the EOM. In order to totally remove this drift, we have developed a complete digital system, based on a DSP kit, to detect and compensate automatically the EOM optical bias point drift and to control simultaneously its temperature. The first technique is based on a dither signal at low frequency, injected to DC electrode of the EOM. The second one is based on the average optical output power of the EOM. A combination of these two techniques can take advantages from both of them. Using like that the OEO, we have tested several configurations to measure the refractive index of four classical chemical solutions leading to a standard deviation of 3 per thousand. The results are in rather good agreement with previous publications. Finally, we have introduced a new method to improve the long-term refractive index measurement by monitoring, with a vector network analyzer, the variations of the optical delay in the fiber loop of the OEO. Introducing by this way a correction to the long-term frequency measurement it is possible to reduce the oscillation frequency fluctuations to only 606 Hz, compared to the 8 GHz of the oscillator, for a duration of 62 hours. Therefore the signal-to-noise ratio in the refractive index measurement can be enhanced and so the detection resolution of the refractive index variations during time
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Azizoḡlu, Murat. "Phase noise in coherent optical communications". Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13463.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1991.Includes bibliographical references (p. 201-206).
by Murat AzizoÄlu.
Ph.D.
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Dove, Justin (Justin Michael). "Phase-noise limitations on nonlinear-optical quantum computing". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89857.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
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Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 57-58).
Flying in the face of the long-sought-after goal of building optical quantum computers, we show that traditional approaches leveraging nonlinear-optical cross phase modulation (XPM) to construct the critical element, the cphase gate - a gate which seeks to impart a [pi]-radian phase shift on a single photon pulse, conditioned on the presence of a second single photon pulse - are doomed to fail. The traditional story told in common textbooks fails to account for the continuous-time nature of the real world. Previous work addressing this fact - finding that that the proper continuous-time theory introduces fidelity-degrading phase noise that precludes such proposals - was limited in scope to the case of co-propagating pulses with equal group velocities. This left room for criticism that a high-fidelity cphase gate might be constructed using XPM with pulses that pass through each other. In our work, we build such a continuous-time quantum theory of XPM for pulses that pass through each other and evaluate its consequences. We find that fundamental aspects of the real world prevent one from constructing a perfect cphase gate, even in theory, and we show that the best we can do seems to fall far short of what is needed for quantum computation, even if we are extremely optimistic.
by Justin Dove.
S.M.
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Farhoudi, Ramtin. "Study of phase noise in optical coherent systems". Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/25706.
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Le bruit de phase est un problème important dans la conception de systèmes cohérents optiques. Bien que le bruit de phase soit étudié énormément dans les communications sans fil, certains aspects de bruit de phase sont nouveaux dans des systèmes cohérents optiques. Dans cette thèse, nous explorons les statistiques de bruit de phase dans les systèmes optiques cohérentes et proposons une nouvelle technique pour améliorer la robustesse du système envers le bruit de phase. Notre première contribution traite de l’étude des statistiques de bruit de phase en présence de compensation électronique de la dispersion chromatique (CD) dans des systèmes cohérents. Nous montrons que le modèle proposé précédemment pour l’interaction de CD avec bruit de phase doit être modifié à cause d’un modèle trop simple pour la récupération de phase. Nous dérivons une expression plus précise pour le bruit de phase estimé par la récupération de phase avec décision dirigée (DD), et utilisons cette expression pour modifier les statistiques de décision pour les symboles reçus. Nous calculons le taux d’erreur binaire (BER) pour le format de transmission DQPSK semi-analytiquement en utilisant nos statistiques de décision modifiées et montrons que pour la récupération de phase idéale, le BER semi-analytique est bien assorti avec le BER simulé avec la technique Monte-Carlo (MC). Notre deuxième contribution est l’adaptation d’une technique de codage MLCM pour les systèmes cohérents limités par le bruit de phase et le bruit blanc additif Gaussien (AWGN). Nous montrons que la combinaison d’une constellation optimisée pour le bruit de phase avec MLCM offre un système robuste à complexité modérée. Nous vérifions que la performance de MLCM dans des systèmes cohérents avec constellations 16-aires se détériorés par le bruit de phase non-linéaire et de Wiener. Pour le bruit de phase non-linéaire, notre conception de MLCM démontre une performance supérieure par rapport àune conception de MLCM déjà présente dans la littérature. Pour le bruit de phase de Wiener, nous comparons deux format de transmission, constellations carrées et optimisée pour bruit de phase, et deux techniques de codage, MLCM et codage à débit uniforme. Nos résultats expérimentaux pour BER après codage suivent les mêmes tendances que le BER simulé et confirment notre conception.Phase noise is an important issue in designing today’s optical coherent systems. Although phase noise is studied heavily in wireless communications, some aspects of phase noise are novel in optical coherent systems. In this thesis we explore phase noise statistics in optical coherent systems and propose a novel technique to increase system robustness toward phase noise. Our first contribution deals with the study of phase noise statistics in the presence of electronic chromatic dispersion (CD) compensation in coherent systems. We show that previously proposed model for phase noise and CD interaction must be modified due to an overly simple model of carrier phase recovery. We derive a more accurate expression for the estimated phase noise of decision directed (DD) carrier phase recovery, and use this expression to modify the decision statistics of received symbols. We calculate bit error rate (BER) of a differential quadrature phase shift keying (DQPSK) system semi-analytically using our modified decision statistics and show that for ideal DD carrier phase recovery the semi-analytical BER matches the BER simulated via Monte-Carlo (MC) technique. We show that the semi-analytical BER is a lower bound of simulated BER from Viterbi-Viterbi (VV) carrier phase recovery for a wide range of practical system parameters. Our second contribution is concerned with adapting a multi-level coded modulation (MLCM) technique for phase noise and additive white Gaussian noise (AWGN) limited coherent system. We show that the combination of a phase noise optimized constellation with MLCM offers a phase-noise robust system at moderate complexity. We propose a numerical method to design set-partitioning (mapping bits to symbols) and optimizing code rates for minimum block error rate (BLER).We verify MLCM performance in coherent systems of 16-ary constellations impaired by nonlinear and Wiener phase noise. For nonlinear phase noise, superior performance of our MLCM design over a previously designed MLCM system is demonstrated in terms of BLER. For Wiener phase noise, we compare optimized and square 16-QAM constellations assuming either MLCM or uniform rate coding. We compare post forward error correction (FEC) BER in addition to BLER by both simulation and experiment and show that superior BLER performance is translated into post FEC BER. Our experimental post FEC BER results follow the same trends as simulated BER, validating our design.
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McBride, Roy. "Phase measurement and phase control in fibre-optic interferometers". Thesis, Heriot-Watt University, 1998. http://hdl.handle.net/10399/1219.
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Ichikawa, Hiroyuki. "Optical beam array generation with phase gratings". Thesis, Heriot-Watt University, 1991. http://hdl.handle.net/10399/807.
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Kakkar, Aditya. "Frequency Noise in Coherent Optical Systems: Impact and Mitigation Methods". Doctoral thesis, KTH, Optik och Fotonik, OFO, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207072.
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The increase in capacity demand along with the advancement in digital signal processing (DSP) have recently revived the interest in coherent optical communications and led to its commercialization. However, design and development of robust DSP algorithms for example for carrier phase recovery (CPR) becomes complex as we opt for high order modulation formats such as 16QAM and beyond. Further, electrical-domain dispersion compensation (EDC), while providing many advantages, makes the system more susceptible to laser frequency noise (FN). For instance, in coherent optical links with post-reception EDC, while the transmitter frequency noise causes only phase impairment, the local oscillator (LO) FN in these systems results in a noise enhancement in both amplitude and phase. This noise is commonly known as equalization enhanced phase noise (EEPN). It results in asymmetric requirements for transmitter laser and LO laser. Further, the system design in the presence of lasers with non-white frequency noise becomes increasingly challenging for increased capacity-distance product. The main contributions of this thesis are, firstly, an experimentally validated theory of coherent optical links with lasers having general non-white frequency noise spectrum and corresponding system/laser design criteria and mitigation technique. Secondly, low complexity and high phase noise tolerant CPR for high order modulation formats. The general theory propounded in this thesis elucidates the origin of the laser frequency noise induced noise enhancement in coherent optical links with different DSP configurations. The thesis establishes the existence of multiple frequency noise regimes and shows that each regime results in different set of impairments. The influence of the impairments due to some regimes can ideally be reduced by optimizing the corresponding mitigation algorithms, while other regimes cause irretrievable impairments. Experimentally validated theoretical boundaries of these regimes and corresponding criteria applicable to system/laser design are provided. Further, an EEPN mitigation method and its two possible implementations are proposed and discussed. The thesis also demonstrates an intrinsic limitation of the conventional Blind Phase Search (BPS) algorithm due to angular quantization and provides methods to overcome it. Finally, this thesis proposes and demonstrates single stage and multi-stage carrier phase recovery algorithms for compensation of phase impairments due to the two lasers for higher order circular and square modulations. The proposed methods outperform the state of art algorithms both in performance and in complexity.QC 20170516
European project ICONE gr. #608099
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Boivin, David. "Optical phase-modulated systems: numerical estimation and experimental measurement of phase jitter". Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-11072006-110448/.
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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2007.Bennett, Gisele, Committee Member ; Rhodes, William, Committee Member ; McLaughlin, Steven, Committee Member ; Barry, John, Committee Co-Chair ; Chang, Gee-Kung, Committee Chair ; Chapman, Michael, Committee Member.
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Bale, Simon. "Ultra high Q resonators and very low phase noise measurement systems for low noise oscillators". Thesis, University of York, 2012. http://etheses.whiterose.ac.uk/3159/.
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This thesis describes research into ultra high Q Bragg resonators, low phase noise measurement systems and low noise oscillators. The thesis is divided into three parts. The first is concerned with the modelling, design and implementation of an extremely high quality factor Bragg resonator. This resonator utilises an aperiodic arrangement of non $\lambda/4$ low loss alumina plates mounted in a cylindrical waveguide. An ABCD parameter waveguide model is developed to simulate and optimise the cavity. The dielectric plates and air waveguide dimensions are optimised using a genetic algorithm to achieve maximum quality factor by redistributing the energy loss within the cavity. An unloaded quality factor ($Q_{0}$) of 196,000 was demonstrated at 9.93 GHz. In the second part the design, implementation and measurement results for an ultra-low noise floor cross correlation residual phase noise measurement system are shown. A measurement noise floor of -200 dBc/Hz is achieved for 100,000 correlations. Residual phase noise measurements are also performed on low noise L-Band microwave amplifiers. The key features of the cross correlation technique and the different window functions required during measurement are discussed. In the third part the residual phase noise performance of several microwave components is evaluated in order to establish their potential utility in a low phase noise oscillator. In the first part of the chapter the designs for a Gallium Nitride (GaN) power amplifier are presented along with the measurements of its noise figure and residual phase noise performance. In the second part of the chapter the designs and performance of an emitter coupled logic (ECL) static digital frequency divider are presented.
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Buseck, David Allan 1963. "High-density CD-ROM readout using direct phase measurement". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276545.
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Direct measurement of optical phase is used in a high-density optical disk reader. The increased density is achieved by introducing multiple pit depths to replace the single pit depths of a traditional compact disk. Having four independent pit depths can double the storage capacity of a disk. The multi-level pits are read by direct measurement of the phase difference between two laser spots focused onto the disk surface. Extraction of phase information utilizes the equations of phase shifting interferometry with four shifted fringe patterns created simultaneously by a compact optical head. The system speed is therefore limited by the readout electronics instead of by slow mechanical phase shifters. The resulting system can identify four independent levels as well as the direction of transition from one level to another. The system also has low sensitivity to vibrations and to changes in the fringe contrast and beam intensity.
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Varnum, Kent C. M. "Noncoherent detection of coherent optical heterodyne signals corrupted by laser phase noise". Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28398.
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Approved for public release; distribution is unlimitedAn error probability analysis is performed for noncoherent detection of optical heterodyne signals corrupted by laser phase noise and additive white Gaussian noise. Two types of laser modulation are investigated, on-off keying (00K) and frequency shift keying (FSK). Single user 00K system performance for different linewidth-to-bit rate ratios is analyzed over a range of both signal-to-noise ratios (SNR) and normalized decision thresholds. The decision threshold analysis illustrates which noise source dominates system performance. An analytical expression representing the effect of laser phase noise on system performance is derived based on a high user bit rate assumption. The system performance obtained with the high bit rate expression is compared with the system performance obtained with currently used expressions to determine its range of validity. An error probability analysis is then performed for noncoherent detection of FSK signals corrupted by laser phase noise and additive white Gaussian receiver noise. The performance of the FSK system is compared with the performance of the 00K system. It is shown that optical FSK systems perform better than optical 00K systems. As a demonstration of future system capability, the performance of a multiuser FSK code-division multiple access (FSK-CDMA) system is analyzed. The results obtained indicate that the application of FSK-CDMA techniques to current wavelength division multiplexed (WDM) systems can increase user capacity up to one thousand fold.
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Gaudy, Thomas. "Statistical Analysis of Equalization Enhanced Phase Noise in Coherent Fiber Optical Communications". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191138.
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Coherent optical communications increase the receiver sensitivity and the total capacity. Together with high speed digital signal processing (DSP), compensation for linear transmission impairments (chromatic dispersion, polarization mode dispersion and phase noise) can be achieved. In the past, many algorithms have been developed for this purpose: we offer an overview of those. However, in dispersion unmanaged coherent optical links, even after DSP, the received constellation remains influenced by enhanced noise commonly known as equalization enhanced phase noise (EEPN). Its properties are explained in further details using statistical analysis. Statistical properties of EEPN are compared with that of additive white gaussian noise (AWGN) and pure phase noise (PN) by numerical simulations complemented with explanation of mean, variance and autocorrelation function. Finally, the possibility to use only digital post-processing for EEPN (similar to PN) is discussed and shown to be not feasible.
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Huang, Zixin. "Protocols for optical quantum metrology". Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18067.
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This thesis explores various protocols which can be applied to quantum metrology, such that precision of the measurement can beat the best classical approaches. We first demonstrate that ancilla-assisted schemes can improve phase estimation in the presence of noise, and we propose an experiment to demonstrate these effects. Given that the use of ancillae helps, it is no surprise that there are noisy channels for which the optimal strategy may depend on the noise level. We show that there is a non-trivial crossover between the ancilla-assisted strategy and the parallel-entangled strategy for Pauli noise channels and the amplitude damping channel. We see that under certain circumstances, the environment cannot access the parameter of interest. We then integrated techniques from quantum communication, to derive a general framework that renders quantum metrology protocols into cryptographic ones. Here the protocol is unconditionally secure if the trusted parties wish only to achieve the standard quantum limit. If Heisenberg-limited precision is to be achieved, they sacrifice some security, where adversaries can access information, but only at the risk of getting caught at it (cheat-sensitivity). In many scenarios, the quantum Fisher information is achieved for only one value of the phase. In a particular phase estimation scheme that measures the parity at the output of a Mach-Zehnder interferometer where the input is a two-mode squeezed vacuum, this problem is particularly imminent. We apply an adaptive technique to resolve this issue, showing that one can achieve precisions substantially below the shot noise limit. The key to a quadratically enhanced improvement in quantum metrology is entanglement. Finally, we demonstrate in a photonic system how high-dimensional entanglement can be certified, and provide an alternate interpretation of entanglement from an information-theoretic perspective.
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Radi, Haidar M. "Frequency hopping spread spectrum multiplexing for interferometric optical fibre sensor networks". Thesis, Manchester Metropolitan University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387483.
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Liang, Rongguang. "Measurement of optical phase and polarization in the media and systems of optical data storage". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279811.
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This dissertation presents the measurement of optical phase in the media and systems of optical data storage, polarization dependence of signals from periodic one-dimensional arrays of magnetic domains in magneto-optical media and crystalline domains in amorphous phase-change media, and optical characterization of multilayer stacks used as optical data storage media. Digital signals in optical data storage systems can be encoded in the intensity, polarization or phase of the carrier beam. Both surface structure and material property variations can create a phase modulation at the exit pupil. Current optical data storage systems do not make use of this phase modulation and its recovery could increase the strength of the generated signal. We experimentally describe a variant of Zernike's phase-contrast microscope to measure the small phase object, an interferometer to measure the relative optical phase on reflection between amorphous and crystalline regions of the phase-change media of optical data storage, and a method to measure optical phase information in disk system. In order to increase the data density in optical data storage, the wavelength becomes shorter and the numerical aperture of the objective lens becomes higher. In the interaction of the focused beam with a grooved, multilayer disk, the different response to s- and p-polarized light upon reflection from the disk results in different complex-amplitudes and has strong impact on readout and servo signals for the two fundamental components of polarization. Polarization dependence of signals from periodic one-dimensional arrays of magnetic domains in magneto-optical (MO) media and crystalline domains in amorphous phase change (PC) media are studied by theoretical calculation and experiment. Currently, many different multilayer stacks are designed to enhance the contrast of readout signal, reduce noise, increase the storage density and speed, or improve media reliability. A good understanding of the range of values of the optical constants should help to improve the accuracy of optical and thermal design of the storage media. The refractive index n and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.
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Chen, Zhenxiang. "The applications of ultrasonic imaging and signal processing in two-phase flow measurement". Thesis, Cranfield University, 1996. http://dspace.lib.cranfield.ac.uk/handle/1826/10516.
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The applications of ultrasonic imaging and signal processing in two-phase flow measurement have been investigated in this thesis. The scattering by single and many scatterers was studied experimentally and numerically. The statistical properties of the scattered waves from many scatterers were examined and the corresponding results are presented. Ultrasonic transmission/reflection mode tomography was introduced. The theories of reflection mode computerised tomography were developed, by which reflectivity functions and scattering amplitude functions can be reconstructed. Image restoration and interpretation methods are presented. Computer simulation of ultrasonic measurements were carried out. A ultrasonic tomographic imaging system was developed, in which fan-shaped sound beam insonification was employed. Static physical models were used to simulate two-phase flows. In order to speed up the data acquisition of a tomographic imaging system, the single receiver mode and multiple receiver mode data acquisition arrangements were studied by experiments. Experiments on imaging small and large objects were carried out. Several signal and image processing methods were examined. A modified histogram equalisation algorithm was developed for processing the resultant ultrasonic images. The experiment results show that the proposed image reconstruction methods are satisfactory. Possible future developments are proposed.
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Patterson, Steven Gregory. "Quantum intensity noise correlation in a Type-II phase matched optical parametric oscillator". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36977.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 104-105).
by Steven Gregory Patterson.
M.S.
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Cardenas, Olaya Andrea. "Digital instrumentation for the measurement of high spectral purity signals". Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCD019/document.
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Les progrès sur la technologie électronique pendant les dernières années avaient permis l’utilisation des techniques numériques dans la métrologie de temps et fréquence où bas bruit et haute précision sont nécessaires. Ces techniques génèrent systèmes plus flexibles pour l’implémentation et pour la configuration. De cette façon, c’est possible d’obtenir systèmes de mesure avec capacités étendues, fonctionnalités ajoutées et plus facile ad utiliser.Les convertisseurs analogique-numérique (ADCs) et numérique-analogique (DACs), considérée comme l’interface avec le monde analogique, représentent la limite de la performance du système en termes de bruit. De plus, en général, les plateformes commerciales basées sur FPGA sont cadencées par un oscillateur à quartz dont précision et stabilité de fréquence ne sont pas adapté pour plupart des applications de temps e fréquence. Dans ce cas, c’est possible d’utiliser le Phase Locked Loop (PLL) intégré dans la FPGA pour générer l’horloge du système à partir d’une référence de fréquence externe. Cependant, en considérant que le bruit de phase du PLL pourrait dégrader la stabilité de la référence et ainsi limiter la performance d’entier système, le PLL devient un composant critique pour l’instrumentation numérique. L’information disponible actuellement dans la littérature décrit en détail les spécifications de ces composants a offset de fréquence loin de la porteuse. Cependant, l’information proche à la porteuse est une préoccupation plus importante pour les applications de temps et fréquence.Dans ce cadre, ma thèse de doctorat est concentrée sur l’étude des limitations des composants critiques de l’instrumentation numérique pour la métrologie de temps et fréquence. L’objectif est de caractériser le bruit introduit par ces composants et ainsi obtenir un modèle que permettra de prédire leurs effets sur une application spécifique. On propose une méthode pour extraire les paramètres des modelés lequel est testé et validé sur la plateforme commercial Red Pitaya. Cette plateforme est une open source embedded system dont résolution et vitesse (14 bit, 125 MSps) sont raisonnablement proche de l’état de l’art des ADCs et DACs (16 bit, 350 MSps or 14 bit, 1 GSps/3GSPs) et c’est potentiellement suffisant pour l’implémentation de un instrument complet. Les résultats de la caractérisation conduisent aux limitations de la plateforme et donnent une directrice pour le design de l’instrument.Basé sur les résultats obtenus de la caractérisation du bruit, l’implémentation de un instrument numérique pour le transfert de fréquence par fibre optique est été réalisée sur la plateforme Red Pitaya. Dans ce projet, une implémentation numérique pour la détection et compensation du bruit de phase induit par la fibre est proposé. Sur la base des résultats de la caractérisation, il était prévu une limitation de la mesure du bruit de phase donnée par le PLL. Les premières mesures de cette implémentation ont été réalisées sur un lien de fibre de 150 km + 150 km placées dans les mêmes câbles entre l'INRiM (Turin) et le Laboratoire Souterrain de Modane (LSM) à la frontière Italie-France. A partir de ces résultats, le bruit introduit par le système numérique a été vérifié en accord avec les résultats de la caractérisation. Additionnel tests et améliorations seront effectués pour avoir un système capable d’être utilisé sur le lien italien pour la fréquence et le temps de Turin à Florence qui est longue de 642 km et à son extension dans le reste de l'Italie prévue dans le prochain avenir.Actuellement, une plateforme plus performante est en cours d'évaluation, à travers les techniques et concepts développés au cours de la thèse. Ce projet a pour but l’implémentation d'un phasemètre à l’état de l’art de la technologie dont l'architecture est basée sur le DAC. La caractérisation du DAC est en cours de développement et les mesures préliminaires sont également rapportées iciImprovements on electronic technology in recent years have allowed the application of digital techniques in time and frequency metrology where low noise and high accuracy are required, yielding flexibility in systems implementation and setup. This results in measurement systems with extended capabilities, additional functionalities and ease of use.The Analog to Digital Converters (ADCs) and Digital to Analog Converters (DACs), as the system front-end, set the ultimate performance of the system in terms of noise. Moreover, most commercial platforms based on FPGA are clocked by quartz oscillators whose accuracy and frequency stability are not suitable for many time and frequency applications. In this case, it is possible to take advantage of the internal Phase Locked Loop (PLL) for generating the internal clock from an external frequency reference. However, the PLL phase noise could degrade the oscillator stability thereby limiting the entire system performance becoming a critical component for digital instrumentation. The information available currently in literature, describes in depth the features of these devices at frequency offsets far from the carrier. However, the information close to the carrier is a more important concern for time and frequency applications.In this frame, my PhD work is focused on understanding the limitations of the critical blocks of digital instrumentation for time and frequency metrology. The aim is to characterize the noise introduced by these blocks and in this manner to be able to predict their effects on a specific application. This is done by modeling the noise introduced by each component and by describing them in terms of general and technical parameters. The parameters of the models are identified and extracted through the corresponding method proposed accordingly to the component operation. This work was validated by characterizing a commercially available platform, Red Pitaya. This platform is an open source embedded system whose resolution and speed (14 bit, 125 MSps) are reasonably close to the state of the art of ADCs and DACs (16 bit, 350 MSps or 14 bit, 1 GSps/3GSPs) and it is potentially sufficient for the implementation of a complete instrument. The characterization results lead to the noise limitations of the platform and give a guideline for instrumentation design techniques.Based on the results obtained from the noise characterization, the implementation of a digital instrument for frequency transfer using fiber link was performed on the Red Pitaya platform. In this project, a digital implementation for the detection and compensation of the phase noise induced by the fiber is proposed. The beat note, representing the fiber length variations, is acquired directly with a high speed ADC followed by a fully digital phase detector. Based on the characterization results, it was expected a limitation in the phase noise measurement given by the PLL. First measurements of this implementation were performed using the 150 km-long buried fibers, placed in the same cables between INRiM and the Laboratoire Souterrain de Modane (LSM) on the Italy-France border. The two fibers are joined together at LSM to obtain a 300 km loop with both ends at INRiM. From these results the noise introduced by the digital system was verified in agreement with characterization results. Further test and improvements will be performed for having a finished system which is intended to be used on the Italian Link for Frequency and Time from Turin to Florence that is 642-km long and to its extension in the rest of Italy that is foreseen in the next future.Currently, a higher performance platform is under assessment by applying the tools and concepts developed along the PhD. The purpose of this project is the implementation of a state of the art phasemeter whose architecture is based on the DAC. The DAC characterization is under development and preliminary measurements are reported here
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Hurley, Paul Raymond. "Application of Optical Fiber Sensors for Quenching Temperature Measurement". Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99035.
Texto completo da fonteResumo:
The critical heat flux (CHF) point for a reactor core system is one of the most important
factors to discuss in regards to reactor safety. If this point is reached, standard coolant
systems are not enough to handle the temperature increase in the cladding, and the likelihood
of meltdown greatly increases. While the nucleate boiling and film boiling regimes have
been well-investigated, the transition boiling regime between the point of departure from
nucleate boiling (DNB) and the minimum film boiling temperature (Tmin) remains difficult
to study. This is due to both the complexity of the phenomena, as well as limitations
in measurement, where experiments typically utilize thermocouples for temperature data
acquisition. As a result of technological advancement in the field of fiber optics, it is possible
to measure the quenching temperature to a much higher degree of precision. Optical fiber
sensors are capable of taking many more measurements along a fuel simulator length than
thermocouples, which are restricted to discrete points. In this way, optical fibers can act
as an almost continuous sensor, calculating data at a resolution of less than one millimeter
where a thermocouple would only be able to measure at one point. In this thesis, the results
of a series of quenching experiments performed on stainless steel, Monel k500, and Inconel
600 rods at atmospheric pressure, with different subcooling levels and surface roughnesses,
will be discussed. The rewetting temperature measurement is performed to compare results
between thermocouples and optical fiber sensors in a 30 cm rod. These results are further
discussed with regard to future application in two-phase flow experiments.Master of Science
There are multiple types of boiling that can occur depending on the heat transfer capabilities of the system and the power applied to the coolant. The most common is nucleate boiling, where vapor produced at the surface forms bubbles and move away from the surface due to buoyancy. At a high enough power, the bubbles can coalesce into a film and lead to a point at which the liquid coolant can no longer contact the surface. Since vapor is not as effective at transferring heat from the surface, the temperature will increase drastically. In nuclear reactors, this situation (known as departure from nucleate boiling), can quickly lead to a meltdown of the fuel rods. Another important safety parameter in nuclear reactors is the minimum temperature at which this vapor film can be maintained, Tmin. This parameter is a source of significant concern with regard to accident scenarios such as LOCA (loss of coolant accident), where reintroducing coolant to the rods efficiently is of top priority. While much research has been done on nucleate and film boiling, it has been difficult to study the transition period between the two regimes due to both its transient nature and the lack of continuous measurement capabilities. Typically, temperature is measured using thermocouples, which are point-source sensors that do not allow for high spatial resolution over a large area. This thesis deals with the utilization of optical fibers for temperature measurement, which are capable of calculating data at every millimeter, potentially a much more precise measurement system than with the thermocouples. The experiments performed in this paper are quenching experiments, where a rod embedded with thermocouples and an optical fiber is heated to well above Tmin and quickly plunged into a volume of water, in order to view the transition from film to nucleate boiling.
22
Golubović, Boris 1967. "Basic module for an integrated optical phase difference measurement and correction system". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/37996.
Texto completo da fonte
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HOLM, DAVID ALLEN. "QUANTUM THEORY OF MULTIWAVE MIXING (RESONANCE FLUORESCENCE, SATURATION SPECTROSCOPY, MODULATION, PHASE CONJUGATION, QUANTUM NOISE)". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187980.
Texto completo da fonteResumo:
This dissertation formulates and applies a theory describing how one or two strong classical waves and one or two weak quantum mechanical waves interact in a two-level medium. The theory unifies many topics in quantum optics, such as resonance fluorescence, saturation spectroscopy, modulation spectroscopy, the build up of laser and optical bistability instabilities, and phase conjugation. The theory is based on a quantum population pulsation approach that resembles the semiclassical theories, but is substantially more detailed. Calculations are performed to include the effects of inhomogeneous broadening, spatial hole burning, and Gaussian transverse variations. The resonance fluorescence spectrum in a high finesse optical cavity is analyzed in detail, demonstrating how stimulated emission and multiwave processes alter the spectrum from the usual three peaks. The effects of quantum noise during the propagation of weak signal and conjugate fields in phase conjugation and modulation spectroscopy are studied. Our analysis demonstrates that quantum noise affects not only the intensities of the signal and conjugate, but also their relative phase, and in particular we determine a quantum limit to the semiclassical theory of FM modulation spectroscopy. Finally, we derive the corresponding theory for the two-photon, two-level medium. This yields the first calculation of the two-photon resonance fluorescence spectrum. Because of the greater number of possible interactions in the two-photon two-level model, the theoretical formalism is considerably more complex, and many effects arise that are absent in the one-photon problem. We discuss the role of the Stark shifts on the emission spectrum and show how the Rayleigh scattering is markedly different.
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CARDENAS, OLAYA ANDREA CAROLINA. "Digital instrumentation for the measurement of high spectral purity signals". Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2687860.
Texto completo da fonteResumo:
Improvements on electronic technology in recent years have allowed the application of digital techniques in time and frequency metrology where low noise and high accuracy are required, yielding flexibility in systems implementation and setup. This results in measurement systems with extended capabilities, additional functionalities and ease of use.
The Analog to Digital Converters (ADCs) and Digital to Analog Converters (DACs), as the system front-end, set the ultimate performance of the system in terms of noise. The noise characterization of these components will allow performing punctual considerations on the study of the implementation feasibility of new techniques and for the selection of proper components according to the application requirements. Moreover, most commercial platforms based on FPGA are clocked by quartz oscillators whose accuracy and frequency stability are not suitable for many time and frequency applications. In this case, it is possible to take advantage of the internal Phase Locked Loop (PLL) for generating the internal clock from an external frequency reference. However, the PLL phase noise could degrade the oscillator stability thereby limiting the entire system performance becoming a critical component for digital instrumentation. The information available currently in literature, describes in depth the features of these devices at frequency offsets far from the carrier. However, the information close to the carrier is a more important concern for time and frequency applications.
In this frame, my PhD work is focused on understanding the limitations of the critical blocks of digital instrumentation for time and frequency metrology. The aim is to characterize the noise introduced by these blocks and in this manner to be able to predict their effects on a specific application. This is done by modeling the noise introduced by each component and by describing them in terms of general and technical parameters. The parameters of the models are identified and extracted through the corresponding method proposed accordingly to the component operation. This work was validated by characterizing a commercially available platform, Red Pitaya. This platform is an open source embedded system whose resolution and speed (14 bit, 125 MSps) are reasonably close to the state of the art of ADCs and DACs (16 bit, 350 MSps or 14 bit, 1 GSps/3GSPs) and it is potentially sufficient for the implementation of a complete instrument. The characterization results lead to the noise limitations of the platform and give a guideline for instrumentation design techniques.
Based on the results obtained from the noise characterization, the implementation of a digital instrument for frequency transfer using fiber link was performed on the Red Pitaya platform. In this project, a digital implementation for the detection and compensation of the phase noise induced by the fiber is proposed. The beat note, representing the fiber length variations, is acquired directly with a high speed ADC followed by a fully digital phase detector. Based on the characterization results, it was expected a limitation in the phase noise measurement given by the PLL. First measurements of this implementation were performed using the 150 km-long buried fibers, placed in the same cables between INRiM and the Laboratoire Souterrain de Modane (LSM) on the Italy-France border. The two fibers are joined together at LSM to obtain a 300 km loop with both ends at INRiM. From these results the noise introduced by the digital system was verified in agreement with characterization results. Further test and improvements will be performed for having a finished system which is intended to be used on the Italian Link for Frequency and Time from Turin to Florence that is 642-km long and to its extension in the rest of Italy that is foreseen in the next future.
Currently, a higher performance platform is under assessment by applying the tools and concepts developed along the PhD. The purpose of this project is the implementation of a state of the art phasemeter whose architecture is based on the DAC. In order to estimate the ultimate performance of the instrument, the DAC characterization is under development and preliminary measurements are also reported here.
25
Arnison, Matthew Raphael. "Phase control and measurement in digital microscopy". Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/569.
Texto completo da fonteResumo:
The ongoing merger of the digital and optical components of the modern microscope is creating opportunities for new measurement techniques, along with new challenges for optical modelling. This thesis investigates several such opportunities and challenges which are particularly relevant to biomedical imaging. Fourier optics is used throughout the thesis as the underlying conceptual model, with a particular emphasis on three--dimensional Fourier optics. A new challenge for optical modelling provided by digital microscopy is the relaxation of traditional symmetry constraints on optical design. An extension of optical transfer function theory to deal with arbitrary lens pupil functions is presented in this thesis. This is used to chart the 3D vectorial structure of the spatial frequency spectrum of the intensity in the focal region of a high aperture lens when illuminated by linearly polarised beam. Wavefront coding has been used successfully in paraxial imaging systems to extend the depth of field. This is achieved by controlling the pupil phase with a cubic phase mask, and thereby balancing optical behaviour with digital processing. In this thesis I present a high aperture vectorial model for focusing with a cubic phase mask, and compare it with results calculated using the paraxial approximation. The effect of a refractive index change is also explored. High aperture measurements of the point spread function are reported, along with experimental confirmation of high aperture extended depth of field imaging of a biological specimen. Differential interference contrast is a popular method for imaging phase changes in otherwise transparent biological specimens. In this thesis I report on a new isotropic algorithm for retrieving the phase from differential interference contrast images of the phase gradient, using phase shifting, two directions of shear, and non--iterative Fourier phase integration incorporating a modified spiral phase transform. This method does not assume that the specimen has a constant amplitude. A simulation is presented which demonstrates good agreement between the retrieved phase and the phase of the simulated object, with excellent immunity to imaging noise.
26
Rizzo, Carlo Anthony Edward. "Phase retrieval near-field/far-field measurement techniques for quasi-optical large apertures". Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310888.
Texto completo da fonte
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Alaulamie, Arwa A. "Nanoscale Temperature Measurement of Phase Transition in Water Using Novel Optical Thermometry Techniques". Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1493904666617419.
Texto completo da fonte
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Thompson, Michael Thomas. "Fast amplitude and delay measurement for characterization of optical devices". Texas A&M University, 2006. http://hdl.handle.net/1969.1/4440.
Texto completo da fonteResumo:
A fast measurement technique based on the modulation phase-shift technique is
developed to measure the wavelength-dependent magnitude and phase responses of
optical devices. The measured phase response is in the form of group delay, which is
used to determine the chromatic dispersion in the device under test by taking the
derivative of the group delay with respect to optical wavelength. The measurement
setup allows both step-tunable and sweeping laser sources. A modulation frequency of
up to 2.7 GHz is accommodated. An alternate method for the phase measurement that
overcomes non-linearities in the measurement setup is also presented. The speed of the
measurement setup is limited by the sweeping speed of the laser source, which for the
Agilent 81682A is 40 nm/sec. The magnitude accuracy is determined by taking a
comparison to the commercially available Micron Finisar measurement system, where
an error of 0.125 dB is noted. The phase accuracy of the measurement setup is tested
by taking the Hilbert transform of the measured magnitude response of an Acetylene
gas cell and comparing it to the integral of the measured group delay. The average
deviation between the two methods is 0.1 radians. An Acetylene gas cell, fiber Bragg
grating, and chirped Bragg grating are tested with the measurement setup and the
Agilent 8168The characterization of the setup leads to the conclusion that the measurement setup
developed in this paper is fast and accurate. The speed of the technique is on the order
of microseconds for a single measurement and excels beyond the speed of the standard
modulation phase-shift technique, which includes measurement times on the order of
minutes. The accuracy of the technique is within 0.125 dB for magnitude
measurements and 0.1 radians for phase measurements when compared to
commercially available measurement systems.2A laser source at 40 nm/sec and the measurement plots are presented.
29
Arnison, Matthew Raphael. "Phase control and measurement in digital microscopy". University of Sydney. Physics, 2003. http://hdl.handle.net/2123/569.
Texto completo da fonteResumo:
The ongoing merger of the digital and optical components of the modern microscope is creating opportunities for new measurement techniques, along with new challenges for optical modelling. This thesis investigates several such opportunities and challenges which are particularly relevant to biomedical imaging. Fourier optics is used throughout the thesis as the underlying conceptual model, with a particular emphasis on three--dimensional Fourier optics. A new challenge for optical modelling provided by digital microscopy is the relaxation of traditional symmetry constraints on optical design. An extension of optical transfer function theory to deal with arbitrary lens pupil functions is presented in this thesis. This is used to chart the 3D vectorial structure of the spatial frequency spectrum of the intensity in the focal region of a high aperture lens when illuminated by linearly polarised beam. Wavefront coding has been used successfully in paraxial imaging systems to extend the depth of field. This is achieved by controlling the pupil phase with a cubic phase mask, and thereby balancing optical behaviour with digital processing. In this thesis I present a high aperture vectorial model for focusing with a cubic phase mask, and compare it with results calculated using the paraxial approximation. The effect of a refractive index change is also explored. High aperture measurements of the point spread function are reported, along with experimental confirmation of high aperture extended depth of field imaging of a biological specimen. Differential interference contrast is a popular method for imaging phase changes in otherwise transparent biological specimens. In this thesis I report on a new isotropic algorithm for retrieving the phase from differential interference contrast images of the phase gradient, using phase shifting, two directions of shear, and non--iterative Fourier phase integration incorporating a modified spiral phase transform. This method does not assume that the specimen has a constant amplitude. A simulation is presented which demonstrates good agreement between the retrieved phase and the phase of the simulated object, with excellent immunity to imaging noise.
30
Iglesias, Olmedo Miguel. "Impairment Mitigation in High Capacity and Cost-efficient Optical Data Links". Doctoral thesis, KTH, Optik och Fotonik, OFO, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208101.
Texto completo da fonteResumo:
The work presented in this thesis fits within the broader area of fiber optics communications. This is an important area of research as it provides a breeding ground for the present and future technologies supporting the Internet. Due to the ever-increasing bandwidth demands worldwide, the network infrastructures that make up the Internet are continuously being upgraded. This thesis aims to identify key segments of the Internet that are deemed to become the Internet's bottleneck if new technology does not replace the current one. These are datacenter intra and inter-connects, and metropolitan core area networks. In each category, we provide a comprehensive overview of the state of the art, identify key impairments affecting data transmission, and suggest solutions to overcome them. For datacenter intra and inter-connects, the key impairments are lack of bandwidth from electro-optic devices, and dispersion. Solutions attempting to tackle these impairments must be constrained by cost and power consumption. The provided solution is MultiCAP, an alternative advanced modulation format that is more tolerable to dispersion and provides bandwidth management features, while being flexible enough to sacrifice performance in order to gain simplicity. MultiCAP was the first advanced modulation format to achieve over 100~Gb/s in 2013 for a data-center interconnect and set the world record on data transmission over a single VCSEL in 2014 for a short reach data link. On metro-core networks, the challenge is to efficiently mitigate carrier induced frequency noise generated by modern semiconductor lasers. We point out that, when such lasers are employed, the commonly used laser linewidth fails to estimate system performance, and we propose an alternative figure of merit we name "Effective Linewidth". We derive this figure of merit analytically, explore it by numerical simulations and experimentally validate our results by transmitting a 28~Gbaud DP-16QAM over an optical link.QC 20170602
GRIFFON
31
Clark, David C. "Digital Holographic Measurement of Nanometric Optical Excitation on Soft Matter by Optical Pressure and Photothermal Interactions". Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4299.
Texto completo da fonteResumo:
In this dissertation we use digital holographic quantitative phase microscopy to observe and measure phase-only structures due to induced photothermal interactions and nanoscopic structures produced by photomechanical interactions. Our use of the angular spectrum method combined with off-axis digital holography allows for the successful hologram acquisition and processing necessary to view these phenomena with nanometric and, in many cases, subnanometric precision. We show through applications that this has significance in metrology of bulk fluid and interfacial properties.
Our accurate quantitative phase mapping of the optically induced thermal lens in media leads to improved measurement of the absorption coefficient over existing methods. By combining a mathematical model describing the thermal lens with that describing the surface deformation effect of optical radiation pressure, we simulate the ability to temporally decouple the two phenomena. We then demonstrate this ability experimentally as well as the ability of digital holography to clearly distinguish the phase signatures of the two effects. Finally, we devise a pulsed excitation method to completely isolate the optical pressure effect from the thermal lensing effect.
We then develop a noncontact purely optical approach to measuring the localized surface properties of an interface within a system using a single optical pressure pulse and a time-resolved digital holographic quantitative phase imaging technique to track a propagating nanometric capillary disturbance. We demonstrate the method's ability to accurately measure the surface energy of pure media and chemical monolayers formed by surfactants with good agreement to published values. We discuss the possible adaptation of this technique to applications for living biological cell membranes.
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Zemba, Michael J. "Site Characterization of Phase Instability via Interferometer Measurement". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1383565461.
Texto completo da fonte
33
Dowsett, Amy. "The improvement of vehicle noise variability through the understanding of phase angle and NVH analysis methods". Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/35880.
Texto completo da fonteResumo:
Noise, vibration and harshness (NVH)levels in the luxury automotive industry are used by customers as a subjective method of determining the vehicle quality. This can be achieved by adjusting the vehicle design, where simulations are used to predict the NVH behaviour. Changes can be expensive and time consuming when made after the design stage has been completed, so it is important to produce accurate simulations of the product. Variability exists to some extent in all products, even those just off the production line, however, if a high level of variability exists then only a small portion of products will meet the predicted behaviour. The aim of the project is to provide information that may lead to the reduction of variability in an automotive vehicle. This is achieved by quantifying the statistical spread of FRFs (frequency response function) in a set of nominally identical vehicles. Once overall levels have been calculated, the location of the most variable sources can be identified. Project also seeks to develop new methods of analysis for the system phase response to determine whether further information may be extracted compared to the magnitude response. There are three main themes that run throughout this thesis, with the first being the quantification of variability due to the measurement taking process which is covered in chapter 3. A novel application of a method to separate the measurement variability from the overall system uncertainty was achieved as well as the quantification of the vehicle to- vehicle variability. The second theme that runs through the study concerns the identification of variability sources. This is realised in chapter 4 and chapter 6 as a set of structural and acoustic tests on a luxury sedan door. The trim was found to be held to the door panel by a series of 11 polymer clips and 4 metal screws. The variability of small changes to a significant boundary condition at the door trim was quantified, showing that the removal of rigid clips had a more significant effect on the overall variability that if a loose clip has been removed. It was also found that clips at the corners were the most sensitive to change. The final theme outlines and tests new analysis methods on the phase and compares the statistical spread of the phase with the equivalent spread of the magnitude. Data taken from the same tests was used and for most of the cases the two results were found to be approximately the same.
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Elliott, Timothy John. "Chromatic dispersion measurement in single-mode optical fibers by acousto-optic modulation and phase detection". Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101274.
Texto completo da fonteResumo:
A system to measure chromatic dispersion in single-mode optical fibers with near point wavelength resolution is described. Differential propagation constant data for the test fiber is collected by using an acousto-optic modulator to frequency-shift laser light passed to an optical heterodyne. Theoretical developments include a frequency-domain calculation technique for interpreting empirical results. The system is proven infeasible, however, due to inherent noise sensitivityM.S.
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Jiang, Bo. "A Wide Band Adaptive All Digital Phase Locked Loop With Self Jitter Measurement And Calibration". ScholarWorks @ UVM, 2016. http://scholarworks.uvm.edu/graddis/562.
Texto completo da fonteResumo:
The expanding growth of mobile products and services has led to various wireless communication standards that employ different spectrum bands and protocols to provide data, voice or video communication services. Software deffned radio and cognitive radio are emerging techniques that can dynamically integrate various standards to provide seamless global coverage, including global roaming across geographical regions, and interfacing with different wireless networks. In software deffned radio and cognitive radio, one of the most critical RF blocks that need to exhibit frequency agility is the phase lock loop (PLL) frequency synthesizer. In order to access various standards, the frequency synthesizer needs to have wide frequency tuning range, fast tuning speed, and low phase noise and frequency spur. The traditional analog charge pump frequency synthesizer circuit design is becoming diffcult due to the continuous down-scalings of transistor feature size and power supply voltage. The goal of this project was to develop an all digital phase locked loop (ADPLL) as the alternative solution technique in RF transceivers by taking advantage of digital circuitry's characteristic features of good scalability, robustness against process variation and high noise margin. The targeted frequency bands for our ADPLL design included 880MHz-960MHz, 1.92GHz-2.17GHz, 2.3GHz-2.7GHz, 3.3GHz-3.8GHz and 5.15GHz-5.85GHz that are used by wireless communication standards such as GSM, UMTS, bluetooth, WiMAX and Wi-Fi etc.
This project started with the system level model development for characterizing ADPLL phase noise, fractional spur and locking speed. Then an on-chip jitter detector and parameter adapter was designed for ADPLL to perform self-tuning and self-calibration to accomplish high frequency purity and fast frequency locking in each frequency band. A novel wide band DCO is presented for multi-band wireless application. The proposed wide band adaptive ADPLL was implemented in the IBM 0.13µm CMOS technology. The phase noise performance, the frequency locking speed as well as the tuning range of the digitally controlled oscillator was assessed and agrees well with the theoretical analysis.
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Mohammed, Abdul Rehman Ansari [Verfasser]. "Quantitative measurement of cellular dynamics using spectral domain optical coherence phase microscopy / Rehman Ansari Mohammed Abdul". Lübeck : Zentrale Hochschulbibliothek Lübeck, 2013. http://d-nb.info/1044432845/34.
Texto completo da fonte
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Si, Chen. "The quantitative analysis of optical phase measurement and its application to the determination of corneal birefringence". Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/38442/.
Texto completo da fonteResumo:
In this thesis, a phase sensitive interferometer is successfully implemented to perform birefringent object surface-profile measurement, based on a polarisation adjustment approach. Using monochromatic light, a novel polarization interferometric method is developed, incorporating the birefringence technique and a waveplate. In our experiments, a birefringent wedge is designed for generating carrier fringes in the polariscope. Retardance is calculated from phase shifting using a phase matching technique. The accuracy of the method has been demonstrated to have an error of less than 0.02 radians. The accuracy and resolution quantitative analysis presented in this thesis can be used to determine accurately the phase-shifting interferometry for high-precision surface profile and bio-structure, such as fibre and collagen measurements with low cost. FFT technique and phase-stepping methods are described to determine birefringence within the cornea. The distribution of human corneal lamellar collagen is determined through a microscopic technique using the combination of a circular polariser and a quarter-wave retarder. A quantitative measure of corneal birefringence is achieved by phase unwrapping. The experimental findings of elliptic and hyperbolic populations of collagen fibrils may explain the optical phenomena of central corneal retardation with biaxial-like behaviour in more peripheral areas. A low cost, simple, and direct approach has been developed to make the required microscopic measurement. The traditional transmission system is improved by applying a reflection system with an LED light source and is suitable for the analysis of the birefringent cornea structures in vivo. A further instrument based upon a synthetic aperture approach has been created with the purpose of measuring the three dimensional birefringence structure of the cornea. The concept of the instrument is a combination of the parallax between individual lenses and the numerically generated planes of focus to visualise the phase structure.
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Hendawy, Mamdouh Fatt-Halla Mohamed. "The application of phase sensitive techniques to the measurement of displacement using optical position sensitive detectors". Thesis, University of Kent, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396406.
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Gates, James Christopher. "Measurement of the local optical phase and amplitude in photonic devices using scanning near-field microscopy". Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/15469/.
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This thesis presents the optical characterisation of various photonic devices using scanning near-field microscopy (SNOM). The SNOM technique has a unique capability of achieving a resolution beyond the diffraction limit. Placing the SNOM into the arm of a heterodyne interferometer also enables the measurement of both the optical phase and amplitude in the near infrared. In this work three different photonic devices are investigated. The optical field distribution within a fibre Bragg grating is investigated as a function of wavelength. This work details the direct observation of the spatial shift of the standing wave across the stop band of a fibre grating. The shift is an explicit feature of fibre Bragg gratings and has previously only been theoretically predicted. The thesis also details three analytical techniques for measuring the microscopic loss of planar or channel waveguides. Two of the techniques are experimentally tested. The techniques exploit a standing wave generated within the waveguide, the visibility of the standing wave provides sufficient information to determine to loss between two points. The present limitations of the techniques are presented. The SNOM technique has also been applied to the measurement of a large mode holey fibre. The work details the accurate characterisation of the mode at the end face of the fibre and as it propagates into free space. The results are compared to theoretically predicted modes.
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Pourbahri, Babak. "Erbium-doped fibre amplifiers and their effects on the phase noise of optical carriers and radio-over-fibre signals". Thesis, University of Kent, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369689.
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Hastings, Robert. "Use of multi-scale phase-based methods to determine optical flow in dynamic scene analysis". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2003. https://ro.ecu.edu.au/theses/1487.
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Estimates of optical flow in images can be made by applying a complex periodic transform to the images and tracking the movement of points of constant phase in the complex output. This approach however suffers from the problem that filters of large width give information only about broad scale image features, whilst those of small spatial extent (high resolution) cannot track fast motion, which causes a feature to move a distance that is large compared to the filter-size. A method is presented in which the flow is measured at different scales, using a series of complex filters of decreasing width. The largest filter is used to give a large scale flow estimate at each image point. Estimates at smaller scales are then carried out by using the previous result as an a priori estimate. Rather than comparing the same region in different images in order to estimate flow, the regions to be compared are displaced from one another by an amount given by the most recent previous flow estimate. This results in an estimate of flow relative to the earlier estimate. The two estimates are then added together to give a new estimate of the absolute displacement. The process is repeated at successively smaller scales. The method can therefore detect small local velocity variations superimposed on the broad scale flow, even where the magnitude of the absolute displacement is larger than the scope of the smaller filters. Without the assistance of the earlier estimates in ‘tuning' the smaller filters in this manner, a smaller filter could fail to capture these velocity variations, because the absolute displacement carry the feature out of range of-the filter during successive frames. The output of the method is a series of scale-dependent flow fields corresponding to different scales, reflecting the fact that motion in the real world is a scale-dependent quantity. Application of the method to some 1 dimensional test images gives good results, with realistic flow values that could be used as an aid to segmentation. Some synthetic 2-dimentional images containing only a small number of well defined features aIso yield good-results but the method performs poorly on a random-dot stereogram and on a real-world test image pair selected from the Hamburg Taxi sequence.
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Muñoz-Arcos, Christian Daniel. "Optical Microwave Signal Generation for Data Transmission in Optical Networks". Thesis, Toulouse, ISAE, 2020. http://www.theses.fr/2020ESAE0013.
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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
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Ballu, Xavier. "Measurement of equilibrium supercurrent noise in superconductor-normal ring and current-phase relation of helical hinge states of tungsten ditelluride". Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASP189.
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Une jonction SNS formée par un matériau non-supraconducteur (N) entre deux contacts supraconducteurs (S) peut être traversée par un supercourant porté par des états liés d'Andreev (ABS) qui est déterminé par la différence de phase supraconductrice aux bornes des contacts supraconducteurs. La valeur de ce courant et sa dynamique sont des sondes très sensibles des propriétés de transport cohérent et topologique dans le matériau non-supraconducteur.Une première expérience dans laquelle un fil mésoscopique (Au) est inséré dans un anneau supraconducteur a permis d'explorer la dynamique des ABS. A température finie, les fluctuations thermiques des ABS doivent donner lieu à des fluctuations du supercourant et donc à une dissipation à fréquence finie dont l'amplitude dépend de leur temps de relaxation comme prédit par le théorème fluctuation-dissipation. En couplant cet anneau à un résonateur supraconducteur nous avons réussi à mesurer indépendamment les fluctuations du supercourant à l'équilibre et la dissipation qui apparait quand on soumet l'anneau à un flux magnétique oscillant. Cette expérience constitue la première confirmation de ce théorème dans une jonction SNS.Dans une seconde partie, nous avons mis en évidence le caractère topologique du ditellure de tungstène (WTe2) à travers la mesure de la relation supercourant/phase en utilisant un dispositif d'interférence quantique supraconducteur (SQUID) asymétrique, constitué de deux jonctions SNS en parallèle. La forme en dent de scie de la relation courant-phase pour une facette latérale du cristal et la survie du supercourant à fort champ magnétique révèlent le caractère balistique et unidimensionnel du transport le long de certaines arêtes sur plus de 500 nm. Ceci est une signature de la présence d'états unidimensionnels protégés du désordre dans ce matériaux confirmant les prédictions d'une phase proche d'un isolant topologique d'ordre supérieur pour ce matériauAn SNS junction formed by a non-superconducting material (N) between two superconducting contacts (S) can sustain a supercurrent carried by Andreev bound states (ABS) which is determined by the superconducting phase difference across the superconducting contacts. The value of this current and its dynamics are very sensitive probes of the coherent and topological transport properties in the non-superconducting material.An initial experiment in which a mesoscopic wire (Au) is inserted into a superconducting ring has made it possible to explore the dynamics of the ABS. At finite temperature, thermal fluctuations in ABS should give rise to fluctuations in the supercurrent and therefore to a finite-frequency dissipation, the amplitude of which depends on their relaxation time, as predicted by the fluctuation-dissipation theorem. By coupling this ring to a superconducting resonator, we were able to measure independently the fluctuations in the supercurrent at equilibrium and the dissipation that occurs when the ring is subjected to an oscillating magnetic flux. This experiment constitutes the first confirmation of this theorem in an SNS junction.In the second part, we demonstrated the topological character of tungsten ditelluride (WTe2) by measuring the supercurrent/phase relation using an asymmetric superconducting quantum interference device (SQUID), consisting of two SNS junctions in parallel. The sawtooth shape of the current-phase relation for a lateral facet of the crystal and the robustness of the supercurrent at high magnetic field reveals the ballistic and one-dimensional character of the transport along certain edges over more than 500 nm. This is a signature of the presence of one-dimensional states protected from disorder in this material, confirming the predictions of a phase close to a higher-order topological insulator for this material
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Wang, Ziyang. "Next Generation Ultrashort-Pulse Retrieval Algorithm for Frequency-Resolved Optical Gating: The Inclusion of Random (Noise) and Nonrandom (Spatio-Temporal Pulse Distortions) Error". Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04122005-224257/unrestricted/wang%5Fziyang%5F200505%5Fphd.pdf.
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Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2005.You, Li, Committee Member ; Buck, John A., Committee Member ; Kvam, Paul, Committee Member ; Kennedy, Brian, Committee Member ; Trebino, Rick, Committee Chair. Vita. Includses bibliographical references.
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Mousa, Pasandi Mohammad. "Adaptive decision-directed channel equalization and laser phase noise induced inter-carrier-inteference mitigation for coherent optical orthogonal frequency division multiplexing transport systems". Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114464.
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The explosive growth of global Internet traffic has placed tremendous strain on both op-tical networks and optical transmission systems, underscoring the need for not only high-capacity transmission links but also for flexible, reconfigurable, and adaptive networks. Re-cent progress in complementary metal–oxide–semiconductor (CMOS) technology has fa-cilitated the use of digital signal processing (DSP) in optical communication systems. Blessed with the revival of coherent optical transmission systems, over the past few years, DSP-enabled, software-defined optical transmission (SDOT) systems have led the funda-mental paradigm shift from inflexible optical networks to robust, reconfigurable, plug-and-play optical networks.Recently, coherent optical orthogonal frequency division multiplexing (CO-OFDM) has been intensively investigated as a promising modulation format for realizing coherent transmission systems. Although CO-OFDM has attracted significant interest in the research community, it has yet to leave a tangible impact on the commercial front due to implemen-tation shortcomings, such as excessive overhead, and susceptibility to fibre nonlinearities and frequency/phase noise.This thesis explores DSP-based solutions for CO-OFDM transmission systems, including two key original contributions. The first contribution is a novel adaptive decision-directed channel equalizer (ADDCE) that aims to reduce the required overhead in CO-OFDM transmission systems. ADDCE retrieves an estimation of the phase noise value after an initial decision making stage, by extracting and averaging the phase drift of all OFDM sub-channels, demonstrating zero-overhead phase noise compensation. Moreover, it updates the channel transfer matrix on a symbol-by-symbol basis, thus enabling a reduction in the associated overhead with pilot symbols. The second original contribution of this thesis focuses on the mitigation of the effect of the laser phase noise induced inter-carrier interfer-ence (ICI) in CO-OFDM systems. This interpolation-based ICI compensator estimates the time-domain phase noise samples using linear interpolation between the common-phase-error (CPE) estimates of consecutive OFDM symbols.The performances of the aforementioned DSP equalization schemes are numerically and experimentally studied in reduced-guard-interval dual-polarization CO-OFDM (RGI-DP-CO-OFDM) transmission systems, and are found to demonstrate superior performance over conventional equalizers (CEs). In addition, a computational complexity analysis of the pro-posed equalizers is provided, which confirms a low implementation complexity.La croissance explosive du trafic globale sur Internet a crée une pression importante sur les réseaux optiques et les systèmes de transmission optiques; ce qui suggère le besoin de liens de transmission de haute capacité ainsi que de réseaux adaptables, reconfigurables et flexible. Les récents progrès dans les technologies de semiconducteurs métal-oxyde com-plémentaire (CMOS) ont facilité l'usage des traitements de signaux numériques (DSP) dans les systèmes de transmission optique. Grâce au retour en force du système de transmission optique cohérent ces dernières années, les systèmes de transmission optique régis par logiciel et supportés par les traitements de signaux numériques ont mené la transition fondamentale des réseaux optique inflexible vers des réseaux optique robuste, reconfigurable, prêt à brancher et utiliser.Depuis peu, le format de modulation par multiplexage fréquentiel orthogonale en optique cohérente (CO-OFDM) est profondément étudier comme format de modulation particu-lièrement prometteur pour réaliser des systèmes de transmission cohérents. Malgré le fait que les CO-OFDM aient réussi à susciter un grand intérêt dans la communauté de recherche, ils leur restent encore à avoir un impact plus tangible dans le secteur commercial. Ce non-déploiement commercial est attribué aux difficultés d'implémentations, notamment à l'information superflue excessive nécessaire et à la susceptibilité accrue aux nonlinéarités de la fibre optique et aux bruits de fréquence et de phase.Cette thèse explore certaines idées de DSP pour des systèmes de transmission CO-OFDM, incluant deux contributions originales. La première étant un égalisateur de canaux à adaptation dirigée par décision (ADDCE) qui vise à réduire l'information superflue nécessaire aux systèmes de transmission CO-OFDM. ADDCE récupère une estimation de la valeur du bruit de phase après un stage initiale de décision en extrayant et en moyennant la dérive de phase de tout les sous-canaux OFDM, ce qui démontre une compensation du bruit de phase sans information superflue. De plus, cela ajourne la matrice de transfère du canal optique symbole par symbole, offrant une réduction de l'information excédante associés avec les symboles pilotes. La seconde contribution de cette thèse se concentre sur la mitiga-tion de l'interférence inter-canaux (ICI) induite par le bruit de phase du laser dans les systèmes CO-OFDM. Ce compensateur de ICI basé sur l'interpolation estime le bruit de phase des échantillons dans le temps en utilisant une interpolation linéaire entre les estimations d'erreur de phase commune (CPE) de symboles OFDM consécutifs. Les performances des algorithmes d'égalisations appliqués en DSP mentionnés ci-haut sont étudiées en simulations et expérimentalement dans un système de transmission en CO-OFDM sur double polarisation à intervalle de garde réduite (RGI-DP-CO-OFDM), ce qui démontre une performance supérieure vis-à-vis de l'égalisateur conventionnel (CEs). Plus encore, l'analyse de la complexité des algorithmes d'égalisateurs proposées sera fournit; confirmant une implémentation à faible complexité.
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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.
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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.
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Coronel-Rico, Juan Fernando. "Étude et réalisation d'un oscillateur à base de VCSEL verrouillé en phase pour des applications en télécommunications". Thesis, Toulouse, ISAE, 2016. http://www.theses.fr/2016ESAE0013/document.
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Les oscillateurs sont présents dans tous les systèmes de communications que nous utilisons. Ils nous permettent de faire la synchronisation entre l’émetteur et le récepteur d’un message. La qualité de cette synchronisation dépend de la stabilité de l’oscillateur. Afin de caractériser cette stabilité dans le domaine fréquentiel, le bruit de phase est utilisé comme paramètre de référence. Un oscillateur qui délivre un signal avec une faible valeur de bruit de phase est un oscillateur de grande pureté spectrale. Les oscillateurs électroniques ont une bonne performance à basse fréquence. En mesure de la demande des systèmes de très haut débit, les oscillateurs électroniques ne sont pas capables de produire signaux qu’avec l’utilisation de multiplicateurs de fréquence qui ajoutent plusieurs éléments à la chaine de communication. Les systèmes hybrides permettent de prendre d’avantage la bonne performance de composants optiques en haute fréquence afin de les intégrer dans les systèmes électroniques et surmonter de cette façon-là les limitations fréquentielles des systèmes électroniques. Ce travail vise l’utilisation de la technique de verrouillage optique par injection du faisceau d’un laser maître vers la cavité d’un VCSEL sous modulation directe dans la boucle d’oscillation. La technique du verrouillage optique du VCSEL permets d’élargir la bande passante de modulation directe du VCSEL et réduire son bruit d’intensité (Relative Intensity Noise - RIN). La réduction du RIN a comme effet secondaire la réduction de la contribution du bruit additif dans l’oscillateur et, en conséquence, la réduction du bruit de phase de l’oscillateurOscillators are present in all telecommunication systems. They synchronize the emitter and receiver of a message. The quality of the synchronization depends on the oscillator stability. To characterize the frequency domain oscillator stability, the phase noise of the carrier is used as figure of merit. An oscillator delivering a low phase noise carrier is a high spectral purity oscillator. Electronic oscillators are high performing at low frequencies. As communications systems require high data rate transmission, the electronic oscillators uses frequency multipliers that degrades the spectral purity of the carrier. The hybrid systems take advantage of the good performance of optical components at high frequency with the goal to be integrated in the electronic systems to overcome frequency limitation issues. This work use the optical injection locking technique by injecting the laser beam of a master laser inside the cavity of a VCSEL under direct modulation. The optical injection locking technique enlarges the direct modulation bandwidth of the VCSEL and reduces the Relative Intensity noise of the laser (RIN). The RIN reduction has as side effect the reduction of the additive noise inside the oscillator and, in consequence, reducing the oscillator phase noise
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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.
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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
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Dašovský, Jakub. "Šumové charakteristiky optického signálu zesíleného optickým vláknovým zesilovačem". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-316415.
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This master thesis deals with problematics of information transmission trough optical fiber and spreading of the electromagnetic field at wavelengths of light. There are analyzed characteristics of the optical signal, and described methods of measuring wavelength of the optical signal power and noise level of the useful signal. Another examined parameter is OSNR at the input and on the output of the optical fiber amplifier EFDA.
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Widjanarko, Taufiq. "Hyperspectral interferometry for single-shot profilometry and depth-resolved displacement field measurement". Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8349.
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A new approach to the absolute measurement of two-dimensional optical path differences is presented in this thesis. The method, which incorporates a white light interferometer and a hyperspectral imaging system, is referred to as Hyperspectral Interferometry. A prototype of the Hyperspectral Interferometry (HSI) system has been designed, constructed and tested for two types of measurement: for surface profilometry and for depth-resolved displacement measurement, both of which have been implemented so as to achieve single shot data acquisition. The prototype has been shown to be capable of performing a single-shot 3-D shape measurement of an optically-flat step-height sample, with less than 5% difference from the result obtained by a standard optical (microscope) based method. The HSI prototype has been demonstrated to be able to perform single-shot measurement with an unambiguous 352 (m depth range and a rms measurement error of around 80 nm. The prototype has also been tested to perform measurements on optically rough surfaces. The rms error of these measurements was found to increase to around 4× that of the smooth surface. For the depth-resolved displacement field measurements, an experimental setup was designed and constructed in which a weakly-scattering sample underwent simple compression with a PZT actuator. Depth-resolved displacement fields were reconstructed from pairs of hyperspectral interferograms. However, the experimental results did not show the expected result of linear phase variation with depth. Analysis of several possible causes has been carried out with the most plausible reasons being excessive scattering particle density inside the sample and the possibility of insignificant deformation of the sample due to insufficient physical contact between the transducer and the sample.