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Zhao, Shiyuan. "Noise, Dynamics and Squeezed Light in Quantum Dot and Interband Cascade Lasers". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAT044.
Pełny tekst źródłaSemiconductor lasers have become ubiquitous in both scientific research and engineering applications, and their miniaturization has made significant strides since their initial demonstration in 1960. Two prominent advancements in this domain include quantum dot (QD) lasers, which operate in the near-infrared wavelength range, and interband cascade lasers (ICLs), designed for mid-infrared operation. Two prominent advancements in this domain include quantum dot (QD) lasers, which operate in the near-infrared wavelength range, and interband cascade lasers (ICLs), designed for mid-infrared operation. In the current landscape of optoelectronics, photonic integrated circuits (PICs) play a pivotal and far-reaching role. They offer unmatched scalability, reduced weight, cost-effectiveness, and energy efficiency by enabling the fabrication of complete optical systems using versatile building blocks seamlessly integrated onto a single chip. In this context, the direct epitaxial growth of III-V materials on silicon holds promise as a compelling approach for the development of coherent laser sources. QD lasers with their ultimate three-dimensional carrier confinement, high thermal stability, and robust tolerance for epitaxial defects are promising candidates for serving as on-chip laser sources. Additionally, ICLs are also well-suited for integration into silicon, making them ideal for compact chemical sensing systems. Noise considerations are indeed paramount when it comes to assessing the quality and reliability of technologies. Achieving the shot noise limit and the Schawlow-Townes linewidth has long been recognized as significant milestones. To tackle noise issues, a range of noise reduction techniques has been explored, encompassing passive optical feedback within an external cavity and active electronic feedback mechanisms to compensate for injection current fluctuations. However, while feedback systems can mitigate laser noise, they can also introduce more intricate nonlinear dynamics, giving rise to phenomena like periodic oscillation, square-wave oscillation, and chaos. The first part of this thesis involves an in-depth investigation into noise and dynamics in two distinct laser types. QD lasers are found to exhibit a high degree of robustness when exposed to parasitic optical reflections but manifest increased sensitivity to optoelectronic feedback. Conversely, ICLs display a spectrum of dynamic behaviours when subjected to optical feedback. Furthermore, recent advancements in low-noise pumping circuits for lasers have led to the generation of amplitude-squeezed light. This represents a transition from classical noise to quantum noise, opening up new possibilities in the field of laser technology and quantum optics. The second part of this thesis delves into the phenomenon of amplitude squeezing in both QD lasers and ICLs. The findings indicate that both types of lasers can exhibit broadband squeezing bandwidth and a significant level of squeezing. All these outcomes in this study contribute to a deeper comprehension of the characteristics of QD lasers and ICLs, laying the groundwork for the development of high-performance classical and quantum emitters on PICs in the future
Fordyce, Jordan. "Single-mode interband cascade lasers for petrochemical process monitoring". Electronic Thesis or Diss., Université de Montpellier (2022-....), 2023. http://www.theses.fr/2023UMONS070.
Pełny tekst źródłaInterband cascade lasers (ICLs) provide sources for the mid-infrared spectral range between 3 – 6 µm with low power consumption and efficient performance. This spectral range is of particular interest to the detection of gases involved with petrochemical processing, such as methane, ethane, and carbon dioxide due to their strong absorption in this range. Correct identification of a gas present in a sample requires single-mode emission and some tuning to match the absorption line, depending on the environmental conditions. Increasing the tuning range possible with one laser source opens up new possibilities in spectroscopic applications. An economical design alternative to what is currently commercially available can be realized through the use of slotted waveguides, which can be fabricated using photolithography, reducing the cost of fabrication.Two new types of ICLs have been designed, fabricated, and studied in this thesis: a single-section slotted ICL and a multi-section slotted Vernier tuned (SVT) ICL. An extensive study of the fabrication step and in particular dry etching was carried out to achieve vertical etching of the materials constituting the ICLs. First, the slotted ICLs were fabricated demonstrating single-mode emission in continuous wave operation at room temperature with emission close to 3.4 µm. Building from this foundation, the SVT ICL was fabricated to extend the tuning range and demonstrate that Vernier tuning could be implemented on this material system
O'Hagan, Seamus. "Multi-mode absorption spectroscopy for multi-species and multi-parameter sensing". Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:6f422683-7c50-47dd-8824-56b4b4ea941d.
Pełny tekst źródłaIkyo, Achakpa Barnabas. "Physical properties of interband and interband cascade edge- and surface-emitting mid-infrared lasers". Thesis, University of Surrey, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549457.
Pełny tekst źródłaAbajyan, Pavel. "Génération et contrôle de peignes de fréquences optiques dans les lasers à cascade d'interbande (ICL)". Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS024.
Pełny tekst źródłaOptical frequency combs (OFCs) are coherent light sources that emit a broad spectrum of discrete, perfectly spaced modes, each with an absolute frequency measurable with the precision of an atomic clock.OFCs in the mid-infrared (MIR 3-12 μm) have recently become of great interest to molecular spectroscopy by the presence of strong absorption of molecular vibration and rotation modes in the spectroscopic "fingerprint" region. Nevertheless, the operation of the OFC in the crucial mid-infrared region (MWIR 3-6 μm) remains significantly underdeveloped compared to other parts of the MIR.In this work, we present an in-depth experimental study of a new generation of interband cascade laser (ICL) and their potential for OFCs in MWIR. The thesis provides proof of the OFC regime both by high-frequency beatnote spectroscopy (BN), and by the new technique of temporal reconstruction of the ultrafast dynamics of these lasers, this making it possible to "visualize" the control of the type of operation of the OFC in ICL. In particular, was carried out the optoelectrical characterization of a set of ICLs with a range of geometries, with the aim of studying low group delay dispersion (GDD) ICLs at longer wavelengths than those previously studied: an ICL operating at 3.8 μm with a 2-section architecture, ICLs operating at 4.1 μm, and another generation of ICL operating at a wavelength of 4.2 μm designed with a wide spectral gain. OFC regime formation and GDD are linked and important for understanding the fundamental mechanisms of OFC formation. ICLs were studied using optical and electrical BN spectroscopy. Passive mode locking (PML) (or free running) and active mode locking (AML) were demonstrated. For 2-section ICLs, where the ICL is divided into a long part and a short part for a single cavity, the exact effect of the small section on the BN has been explained: allows to (a) control very finely the intracavity GDD, (b) introducing losses and showing that we converge towards PML behavior.This work then feeds into the case of ICLs operating at longer wavelengths in a single section cavity and where the GDD is expected to be less. In the particular case of the ICLs operating at 4.1 μm, we demonstrate a strong optical BN, which can be injection locked by radio frequency (RF) injection at the round trip frequency of the ICL, showing the first-steps of active modelocking. This injection locking was achieved using a simple single-section laser architecture with very low waveguide dispersion, and showing that adapting the ICL waveguide for RF operation is not a fundamental requirement. In the final part of the thesis, we show the implementation of the "Shifted Wave Interference Fourier Transform Spectroscopy" (SWIFTS) technique, used in two different configurations, to reconstruct the laser's temporal intensity profile at ultrafast timescales. This permits to demonstrate the nature of OFC generated in these ICLs. Indeed, we show that the ICL operates in the frequency modulation (FM) regime when free-running and transits towards an amplitude modulation (AM) regime when actively modelocked. Interestingly, we also show that ICLs can generate short pulses of ~6.7 ps in free-running operation, despite FM operation, and highlight the control of the pulse width and peak intensity via RF injection. This permits to compress the free-running pulses by a factor of 2.3 to obtain sub-3 ps pulses.This work constitutes an important step in the creation and control of OFCs in the MWIR region. The prospects are to broaden the spectral bandwidth of ICLs and generate high-power ultrashort pulses in the MWIR and beyond
Herdt, Andreas Verfasser], Wolfgang [Akademischer Betreuer] Elsäßer i Thomas [Akademischer Betreuer] [Walther. "The laser-as-detector approach exploiting mid-infrared emitting interband cascade lasers: A potential for spectroscopy and communication applications / Andreas Herdt ; Wolfgang Elsäßer, Thomas Walther". Darmstadt : Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1224048725/34.
Pełny tekst źródłaHerdt, Andreas [Verfasser], Wolfgang [Akademischer Betreuer] Elsäßer i Thomas [Akademischer Betreuer] Walther. "The laser-as-detector approach exploiting mid-infrared emitting interband cascade lasers: A potential for spectroscopy and communication applications / Andreas Herdt ; Wolfgang Elsäßer, Thomas Walther". Darmstadt : Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1224048725/34.
Pełny tekst źródłaPatterson, Steven Gregory. "Bipolar cascade lasers". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/8805.
Pełny tekst źródłaIncludes bibliographical references.
This thesis addresses issues of the design and modeling of the Bipolar Cascade Laser (BCL), a new type of quantum well laser. BCLs consist of multiple single stage lasers electrically coupled via tunnel junctions. The BCL ideally operates by having each injected electron participate in a recombination event in the topmost active region, then tunnel from the valence band of the first active region into the conduction band of the next active region, participate in another recombination event, and so on through each stage of the cascade. As each electron may produce more than one photon the quantum efficiency of the device can, in theory, exceed 100%. This work resulted in the first room temperature, continuous-wave operation of a BCL, with a record 99.3% differential slope efficiency. The device was fully characterized and modeled to include light output and voltage versus current bias, modulation response and thermal properties. A new singlemode bipolar cascade laser, the bipolar cascade antiresonant reflecting optical waveguide laser, was proposed and modeled.
by Steven G. Patterson.
Ph.D.
Williams, Benjamin S. (Benjamin Stanford) 1974. "Terahertz quantum cascade lasers". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17012.
Pełny tekst źródłaIncludes bibliographical references (p. 297-310).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
The development of the terahertz frequency range has long been impeded by the relative dearth of compact, coherent radiation sources of reasonable power. This thesis details the development of quantum cascade lasers (QCLs) that operate in the terahertz with photon energies below the semiconductor Reststrahlen band. Photons are emitted via electronic intersubband transitions that take place entirely within the conduction band, where the wavelength is chosen by engineering the well and barrier widths in multiple-quantum-well heterostructures. Fabrication of such long wavelength lasers has traditionally been challenging, since it is difficult to obtain a population inversion between such closely spaced energy levels, and because traditional dielectric waveguides become extremely lossy due to free carrier absorption. This thesis reports the development of terahertz QCLs in which the lower radiative state is depopulated via resonant longitudinal-optical phonon scattering. This mechanism is efficient and temperature insensitive, and provides protection from thermal backfilling due to the large energy separation between the lower radiative state and the injector. Both properties are important in allowing higher temperature operation at longer wavelengths. Lasers using a surface plasmon based waveguide grown on a semi-insulating (SI) GaAs substrate were demonstrated at 3.4 THz in pulsed mode up to 87 K, with peak collected powers of 14 mW at 5 K, and 4 mW at 77 K.
Additionally, the first terahertz QCLs have been demonstrated that use metalmetal waveguides, where the mode is confined between metal layers placed immediately above and below the active region. These devices have confinement factors close to unity, and are expected to be advantageous over SI-surface-plasmon waveguides, especially at long wavelengths. Such a waveguide was used to obtain lasing at 3.8 THz in pulsed mode up to a record high temperature of 137 K, whereas similar devices fabricated in SI-surface-plasmon waveguides had lower maximum lasing temperatures due to the higher losses and lower confinement factors. This thesis describes the theory, design, fabrication, and testing of terahertz quantum cascade laser devices. A summary of theory relevant to design is presented, including intersubband radiative transitions and gain, intersubband scattering, and coherent resonant tunneling transport using a tight-binding density matrix model. Analysis of the effects of the complex heterostructure phonon spectra on terahertz QCL design are considered. Calculations of the properties of various terahertz waveguides are presented and compared with experimental results. Various fabrication methods have been developed, including a robust metallic wafer bonding technique used to fabricate metal-metal waveguides. A wide variety of quantum cascade structures, both lasing and non-lasing, have been experimentally characterized, which yield valuable information about the transport and optical properties of terahertz devices. Finally, prospects for higher temperature operation of terahertz QCLs are considered.
by Benjamin S. Williams.
Ph.D.
Rochat, Michel. "Far-infrared quantum cascade lasers". Online version, 2002. http://bibpurl.oclc.org/web/24095.
Pełny tekst źródłaDhirhe, Devnath. "Monolithic tuneable quantum cascade lasers". Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4604/.
Pełny tekst źródłabin, Hashim Hasnul Hidayat. "Travelling-wave series cascade lasers". Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493548.
Pełny tekst źródłaCommin, James Paul. "Short wavelength quantum cascade lasers". Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.575411.
Pełny tekst źródłaFreeman, J. R. "Heterogeneous terahertz quantum cascade lasers". Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599209.
Pełny tekst źródłaKischkat, Jan-Ferenc. "External Cavity Quantum Cascade Lasers". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17303.
Pełny tekst źródłaThis thesis thoroughly investigates theoretically and experimentally the effects many physical parameters have on the performance of Tunable External-Cavity Quantum-Cascade Lasers (EC-QCLs). These include, among others, the anti-reflection coating, the type of optics, and the geometrical as well as mechanical and structural properties of the EC setup. This was done by assembling three very different EC setups and comparing and discussing their performance, as well as advantages and disadvantages for different purposes using mainly QCLs from the same original wafer for better comparability. For the last part of this thesis, a new type of EC-QCL configuration was developed with properties so promising that we believe it has the potential to replace the Littrow Cavity in the long term. This is an alignment-stabilized and interference filter-tuned design using a retroreflector as the external reflector. For the demonstration of this concept, development of the tuning element in the form of an angle-tunable high-Q mid-infrared bandpass filter was necessary. For the design of the filter, materials with very strict tolerances on the physical and optical properties were selected from theoretical considerations and a fabrication method with highly optimized process parameters was developed. The first filters on the basis of yttrium fluoride/yttrium oxide/germanium/silicon have a transmission bandwidth of 0.14% of the central wavelength and a peak transmission of approximately 60%. The EC configuration resulted in a sensitivity reduction to mechanical perturbations of the reflector by two orders of magnitude, with a calculated potential for three orders of magnitude using optimized optics. This design lifts the fundamental constraint on miniaturization imposed on the Littrow design that requires large beam diameters to ensure a small bandwidth of the Littrow grating.
Flores, Yuri Victorovich. "Mid-infrared quantum cascade lasers". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17224.
Pełny tekst źródłaTwo decades after their invention in 1994, quantum-cascade lasers (QCLs) become increasingly important in the global infrared optoelectronics market. Photoacoustic spectroscopy, environment monitoring, hot object simulation, and free-space communication systems are selected examples of the current and potential applications of QCLs. Record optical powers as large as 14 W and power-conversion efficiencies ranging between 15-35 % have been reported for MIR QCLs for temperatures 80-300 K. Further improvement of these characteristics depends not only of aspects as heat management and chip-packaging, but also on improving the active-region design to reduce several leakage channels of charge carriers. However, mechanisms through which leakage of charge carriers affects QCLs performance have not been thoroughly researched. A better understanding of the several (non-radiative) scattering mechanisms involved in carrier transport in QCLs is needed to design new structures and optimize their performance. This work provides a realistic description of charge carriers transport in QCLs. We discuss in particular carrier leakage from QCL quantum-well confined states into higher and lower states. The two main mechanisms for non-radiative intersubband scattering in MIR QCLs are electron-longitudinal-optical-phonon scattering and interface roughness-induced scattering. We present methods for the experimental determination of the leakage current in QCLs at and above laser threshold, which allowed us to estimate the sheet distributions of conduction band states and better understand the impact of temperature activated leakage on QCLs characteristics. We found that even at temperatures low enough to neglect ELO scattering, carriers leakage due to IFR becomes significant for devices operating at high electron temperatures. Altogether, this approach offers a straightforward method to analyze and troubleshoot new QCL active region designs and optimize their performance.
Hay, Kenneth Gillespie. "Gas sensing using quantum cascade lasers". Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=12766.
Pełny tekst źródłaHoughton, M. "Gain in terahertz quantum cascade lasers". Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604257.
Pełny tekst źródłaKumar, Sushil Ph D. Massachusetts Institute of Technology. "Development of terahertz quantum-cascade lasers". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40501.
Pełny tekst źródłaIncludes bibliographical references (p. 321-340).
The terahertz or the far-infrared frequency range of the electromagnetic spectrum ( ... ) has historically been technologically underdeveloped despite having many potential applications, primarily due to lack of suitable sources of coherent radiation. Following on the remarkable development of mid-infrared ( ... ) quantum-cascade lasers (QCLs) in the past decade, this thesis describes the development of electrically-pumped terahertz quantum-cascade lasers in GaAs/AlsGal_.As heterostructures that span a spectral range of 1.59 - 5.0 THz ( ... ). A quantum-cascade laser (QCL) emits photons due to electronic intersubband transitions in the quantum-wells of a semiconductor heterostructure. The operation of terahertz QCLs at frequencies below the Reststrahlen band in the semiconductor ( ... ), is significantly more challenging as compared to that of the mid-infrared QCLs. Firstly, due to small energy separation between the laser levels various intersubband scattering mechanisms are activated, which make it difficult to selectively depopulate the lower laser level. Additionally, as electrons gain enough kinetic energy in the upper laser level thermally activated longitudinal-optical (LO) phonon scattering reduces the level lifetime and makes it difficult to sustain population inversion at higher temperatures.
(cont.) Secondly, waveguide design for terahertz mode confinement is also more challenging due to higher free-carrier losses in the semiconducting doped regions at the terahertz frequencies. For successful designs reported in this work, the lower radiative state depopulation is achieved by a combination of resonant-tunneling and fast LO phonon scattering, which allow robust operation even at relatively high temperatures. An equally important enabling mechanism for these lasers is the development of metal-metal waveguides, which provide low waveguides losses, and strong mode confinement due to subwavelength mode localization in the vertical dimension. With these techniques some record performances for terahertz QCLs are demonstrated including the highest pulsed operating temperature of 169 K, the highest continuous-wave (cw) operating temperature of 117 K, and the highest optical power output (248 mW in pulsed and 138 mW in cw at 5 K) for any terahertz QCL. Towards the bigger goal of realizing a 1-THz solid-state laser to ultimately bridge the gap between electronic and optical sources of electromagnetic radiation, QCLs with a unique one-well injection scheme, which minimizes intersubband absorption losses that occur at longer wavelengths, are developed.
(cont.) Based on this scheme a QCL operating at 1.59 THz (A - 189 ym) is realized, which is amongst the lowest frequency solid-state lasers that operate without the assistance of a magnetic field. This thesis also reports on the development of distributed-feedback lasers in metal-metal waveguides to obtain single-mode operation, with greater output power and better beam quality. The subwavelength vertical dimension in these waveguides leads to a strongly coupled DFB action and a large reflection from the end-facets, and thus conventional coupled-mode theory is not directly applicable to the DFB design. A design technique with precise control of phase of reflection at the end-facets is developed with the aid of finite-element analysis, and with some additional unique design and fabrication methods, robust DFB operation has been obtained. Single-mode surface-emitting terahertz QCLs operating up to - 150 K are demonstrated, with different grating devices spanning a range of approximately 0.35 THz around v - 3 THz using the same gain medium. A single-lobed far-field radiation pattern, higher output power due to surface-emission, and a relatively small degradation in temperature performance compared to the Fabry-Perot ridge lasers makes these DFB lasers well suited for practical applications that are being targeted by the terahertz quantum-cascade lasers.
by Sushil Kumar.
Ph.D.
Han, Ningren. "Electrically tunable terahertz quantum cascade lasers". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84723.
Pełny tekst źródłaThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 113-118).
In this thesis, microelectromechanical systems (MEMS) assisted electrically tunable terahertz quantum cascade lasers (THz QCLs) are designed and demonstrated. Two MEMS tuner devices are proposed to achieve electrically tunable THz QCLs. One is the electrostatic comb drive actuated tuner design and the other one is a two-stage flexure design that is actuated by an external piezo nano-positioning actuator. The MEMS tuner devices are all fabricated using standard foundry process SOIMUMPs from MEMSCAP Inc. with some additional in-house post-processings. First order distributed-feedback (DFB) THz wire QCLs with robust mode selectors are designed and fabricated at the MIT Microsystems Technology Laboratories (MTL) using processes developed at our group. By integrating the MEMS tuner chips with the THz QCL chips, broadband electrically tunable THz QCLs are successfully demonstrated. This thesis work provides an important step towards realizing turn-key tunable THz coherent sources for a variety of applications such as THz spectroscopy and THz coherent tomography.
by Ningren Han.
S.M.
Worrall, Christopher Henry. "Long wavelength Terahertz quantum cascade lasers". Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612926.
Pełny tekst źródłaGambari, Johannes. "Nonlinear effects in quantum cascade lasers". Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7824.
Pełny tekst źródłaKundu, Iman. "Frequency tunable terahertz quantum cascade lasers". Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7890/.
Pełny tekst źródłaFujita, Kazuue. "Mid-infrared InGaAs/InAlAs Quantum Cascade Lasers". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/192129.
Pełny tekst źródłaDevenson, Jan. "InAs/AlSb short wavelength quantum cascade lasers". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20101102_153710-37964.
Pełny tekst źródłaDisertaciniame darbe nagrinėjamas InAs/AlSb medžiagų sistemos panaudojimas trumpabangių tarppajuostinių lazerių kūrimui. Buvo išplėtota molekulinių pluoštelių epitaksijos technologija, leidžianti auginti daugiaperiodines neįtemptas InAs/AlSb heterosandūras su mažu 1-2 atominių sluoksnių šiurkštumu. Buvo parodyta, jog InAs/AlSb medžiagų sistema yra tinkama kurti trumpabangiams kvantiniams kaskadiniams lazeriams, veikiantiems žemiau 4 µm bangos ilgio ribos. Buvo ištirtas kvantinių kaskadinių lazerių, turinčių tiek plazmoninius bangolaidžius su stipriai legiruotais InAs apdariniais sluoksniais, tiek ir mažo periodo InAs/AlSb supergardelių bangolaidžius, veikimas bei jų įtaka prietaiso parametrams. Šie sprendimai dėl bangolaidžių bei tolimesni aktyviosios terpės patobulinimai, naudojant piltuvėlio formos injektorių, leido sukurti didelio našumo prietaisus, galinčius veikti iki 420 K temperatūros, esant 3,3 µm bangos ilgio emisijai, ir pasiekti maksimalią optinę galią siekiančią 1 W kambario temperatūroje. Šios inovacijos leido sukurti ir InAs/AlSb kvantinį kaskadinį lazerį, emituojantį ~2,6 µm bangos ilgio spinduliuotę šiai dienai tai yra trumpiausią bangos ilgį spinduliuojantis tokio tipo prietaisas pasaulyje.
Zervos, Charalampos. "Non-linear optics in quantum cascade lasers". Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429194.
Pełny tekst źródłaMc, Tavish James Peter. "Band Structure Effects in Quantum cascade Lasers". Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503285.
Pełny tekst źródłaBloom, Guillaume. "Combinaison cohérente de lasers à cascade quantique". Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00678958.
Pełny tekst źródłaCarder, Damian Andrew. "Studies of GaAs based quantum cascade lasers". Thesis, University of Sheffield, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275215.
Pełny tekst źródłaBurghoff, David Patrick. "Characterization of mid-infrared quantum cascade lasers". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55343.
Pełny tekst źródłaThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 97-99).
Quantum cascade lasers provide some of the highest output powers available for light in the mid-infrared range (from 3 to 8 m). As many of their applications require portability, designs that have a high wall-plug efficiency are essential, and were designed and grown by others to achieve this goal. However, because a large fraction of these devices did not operate at all, very few of the standard laser measurements could be performed to determine their properties. Therefore, measurements needed to be performed that could non-destructively probe the behavior of QCLs while still providing useful information. This thesis explores these types of measurements, all of which fall into the category of device spectroscopy. Through polarization-dependent transmission and photovoltaic spectroscopy, a large portion of the quantum mechanical bandstructure could be determined, along with many of the parameters characterizing crystal growth quality. In addition, high-resolution transmission spectroscopy was used to find the properties of the QCL waveguide. In order to find the correspondence between theory and experiment, bandstructure simulations were performed using a three-band p model, and two-dimensional electromagnetic simulations were performed to describe the laser's optical properties. These simulations were found to be in relatively good agreement with the device measurements, and any discrepancies were found to be consistent with problems in the growth and fabrication.
by David Patrick Burghoff.
S.M.
Alton, Jesse. "Bound-to-continuum THz quantum cascade lasers". Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615160.
Pełny tekst źródłaWilson, David. "Trace gas spectrometry using quantum cascade lasers". Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=18580.
Pełny tekst źródłaMatsuoka, Yohei. "Broadly Tunable External Cavity Quantum Cascade Lasers". Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21073.
Pełny tekst źródłaMid-infrared (mid-IR) technology is a very powerful tool for molecular spectroscopy since vibration modes of many molecules lie in this wavelength range. The External-Cavity Quantum Cascade Laser (EC-QCL) can cover any part of this spectral range. The main goal of this study is to improve EC-QCL performance in terms of wavelength tunability and laser power. The theoretical study about Quantum Cascade Laser (QCL) and EC systems has confirmed that the QCL plays the core role of EC-QCL systems; the power efficiency of an EC system is determined by the combination of the power efficiency of QCL and AR-coating of the laser facet. The width of the tuning range is determined by the gain spectrum of QCL. During this work, QCLs have been fabricated in our group and the optimization of these factors were carried out with various approaches, from QCL growth to facet coatings. One of the major challenges in making EC systems is to reduce the intra-facet reflectivity of the laser chip, and we first proposed a new anti-reflection (AR) coating concept and demonstrated its performance for the first time to the community, achieving good reduction of reflection of the AR-coated substrate over 7-12 μm range, keeping below R < 1% reflection over the entire spectrum. The coating model was applied on broad-gain QCL facets, and the reflection was reduced to 0.75% over the entire emission wavelength range. Furthermore, this work focused on the development and engineering of laser systems, and two compact Littrow-type lasers and an EC system with a new optical configuration have been developed, achieving good performances; tunable from 920 cm-1 to 1190 cm-1 and 0.45 W pulse power. The new type of laser, an Intra-cavity out-coupling EC laser, was also proposed to enhance the power output and achieved over 1 W pulse power with keeping the same tuning range as the Littrow-type.
中赤外分光の技術は非常に有用である。これはとりわけ多くの分子振動モードがこの波長帯域に存在しているためである。可変長レーザーである外部共振器量子カスケードレーザー(External cavity quantum cascade laser, EC-QCL)は、これらスペクトル領域を網羅することが可能で、したがって、EC-QCLは産業スケールを含めた、標準的な光源として非常に潜在的である。商品化のフェーズをさらに推し進めるため、このレーザー性能におけるボトムアップの技術が求められてる。 多くの中赤外光のアプリケーションには広帯域の光源が求められている。この研究はおもにそうした性能を最大化することを背景としている。具体的な目的としては、波長の変調性および光源の強度の向上である。これらの目的に取り組むため、我々はいくつかの段階にステージ化して研究を進めてきた。まず初めに、QCLおよびEC-QCLの基本的な特性の追求から始めた。QCLおよびEC-QCLの物理機構の理論的な考察を行い、これらからEC-QCL形態における要素の最適条件もしくは要請を求めた。QCL素子が、その主要な部位であり、EC系におけるほとんどの性能特性である量子効率、変調領域幅、増幅器の光学損失を決定する。 さまざまなアプローチによりこれら緒特性の最適化が行われた。 この研究のなかで、我々グループ内でシステムの心臓となるQCL素子の全製造プロセス(結晶成長から素子コーティングに至るまで)をおこなった。これら製造手順および性能特性の詳細もまた本論文に記す。 ECレーザーにおける要請特性の中で特に困難な課題として、レーザー素子の内部断面(intra-facet)の反射率の低減があげられる。これに応じるものとして、我々は新たな反射防止膜のコンセプトで、特に中赤外光領域に有益なものを提案した。この実現のために、様々な誘電体物質の光学特性を調べ、中赤外光の応用に最適なものを選択し、実際のコーティングに応用した。ここで提案されたモデル``quasi-Lockhart'' (疑ロックハート)のコーティングは、実験によりその高い性能が実証された。波長7–12 μmの領域をカバーし、かつその全領域内で反射率を1%以下に抑えることができた。またこのコーティングは広帯域ゲインのチップにも施され、その反射率を全体域をカバーしながら、0.75%まで低減させた。この成果はEC-QCLだけでなく、一般の中赤外光の光学コーティングにおいても大いに有用であろう。 さらに、我々は本研究の中でレーザーシステムの構築にも取り組んだ。この研究のなかで、二台のLittrow型レーザーと、新たな光学系をもつECレーザーを構築し、その高性能性を実証した。Littrow型では920 cm-1-1190 cm-1の帯域とパルス強0.45 Wを達成。新たなレーザーシステムであるIntra-cavity out-coupling系は従来の系にくらべ高出力することを目的とされ、その帯域を維持しながら、パルス強1~Wの出力を達成した。またこれら新たなシステムを用いて、またプロジェクトバートナーとの食道癌の細胞イメージングも試験、およびグループにおいてアンモニアの吸光度測定を実施した。
Kirkbride, James M. R. "Coherent transient spectroscopy with quantum cascade lasers". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:c7b897e5-052f-4c15-a3c9-f95ca3b56d70.
Pełny tekst źródłaKeeley, James Thomas. "Self-mixing in terahertz quantum cascade lasers". Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/12509/.
Pełny tekst źródłaFriart, Gaetan. "Semiconductor laser dynamics: two polarization feedback, quantum cascade lasers, and ring lasers". Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/248835.
Pełny tekst źródłaLes lasers à semi-conducteur sont sensibles aux perturbations externes et celles-ci peuvent déstabiliser leur faisceau de sortie d’intensité constante. Ceci est particulièrement marquant quand le laser à semi-conducteur est sujet à un feedback optique, c’est-à-dire quand une partie de la lumière sortant du laser est réinjectée dans sa cavité après réflexion par un miroir distant. Pour certaines applications, cela représente une nuisance que l’on souhaite éviter. Mais le feedback optique peut aussi engendrer des régimes dynamiques utiles pour de nouvelles applications. Dans cette thèse, nous étudions différents problèmes où un laser à semi-conducteur est soumis à un feedback retardé ou à un signal injecté. Nos travaux sont motivés par de récentes expériences, des questions technologiques ou des phénomènes dynamiques particuliers. Nous combinons des techniques analytiques, des simulations numériques ainsi que des expériences afin d’analyser les mécanismes de bifurcation menant à une large variété de régimes oscillants.Nous étudions en premier lieu la dynamique d’un laser à semi-conducteur soumis à un feedback avec rotation de la polarisation. Nous examinons, à la fois théoriquement et expérimentalement, la séquence de bifurcations menant à des oscillations sous forme d’ondes carrées. Nous mettons en évidence une multistabilité entre différentes ondes carrées de périodes spécifiques. Nous introduisons alors un mécanisme de contrôle qui nous permet de sélectionner l’onde carrée désirée. Nous analysons ensuite les frontières de stabilité d’un laser à semi-conducteur à deux polarisations soumis à une injection optique. Nous montrons que si les gains des deux modes de polarisation sont suffisamment proches, un état stationnaire mixte stable peut exister. Nous explorons également les conditions permettant une bistabilité entre un état stationnaire pur et un état stationnaire mixte. Les lasers à cascade quantique sont de nouveaux lasers à semi-conducteur prometteurs qui possèdent une forte tolérance au feedback optique. Nous examinons de façon systématique leur stabilité dans la limite des grands retards. Nous montrons que des instabilités oscillantes sont cependant possibles pour de faibles valeurs du courant de pompe. Le dernier dispositif que nous étudions dans cette thèse est le laser à semi-conducteur en anneau soumis à un feedback optique. Nous identifions le mécanisme de bifurcation, appelé pont de bifurcation, responsable des instabilités oscillantes dans le faisceau de sortie du laser. Ces oscillations sont indésirables pour la plupart des applications impliquant de tels lasers. Nous montrons qu’elles peuvent être évitées en contrôlant la phase du feedback.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Wang, Cheng. "Modulation dynamics of InP-based quantum dot lasers and quantum cascade lasers". Thesis, Rennes, INSA, 2015. http://www.theses.fr/2015ISAR0009/document.
Pełny tekst źródłaHigh performance semiconductor lasers are strongly demanded in the rapidly increasing optical communication networks. Low dimensional nanostructure lasers are expected to be substitutes of their quantum well (Qwell) counterparts in the next-generation of energy-saving and high-bandwidth telecommunication optical links. Many efforts have been devoted during the past years to achieve nanostructure lasers with broad modulation bandwidth, low frequency chirp, and reduced linewidth enhancement factor. Particularly, 1.55-μm InP-based quantum dash (Qdash)/dot (Qdot) lasers are preferable for long-haul transmissions in contrast to the 1.3-μm laser sources. In this dissertation, we investigate the dynamic characteristics of InPbased nanostructure semiconductor lasers operating under direct current modulation, including the amplitude (AM) and frequency (FM) modulation responses, the linewidth enhancement factor (also known as α-factor), as well as large-signal modulation responses. Using a semi-analytical analysis of the rate equation model, it is found that the modulation bandwidth of the quantum dot laser is strongly limited by the finite carrier capture and relaxation rates. In order to study the α- factor and chirp properties of the quantum dot laser, we develop an improved rate equation model, which takes into account the contribution of carrier populations in off-resonant states to the refractive index change. It is demonstrated that the α-factor of quantum dot lasers is strongly dependent on the pump current as well as the modulation frequency, in comparison to the case of Qwell lasers. The α-factor remains constant at low modulation frequencies (<0.1 GHz) and higher than the value derived at high modulation frequencies (beyond several GHz) from the FM/AM technique. These unique features are mostly attributed to the carrier populations in off-resonant states. Further simulations show that the α-factor can be reduced by enlarging the energy separation between the resonant ground state (GS) and off-resonant states. Lasing from the excited state (ES) can be a promising alternative to enhance the laser’s dynamic performance. The laser exhibits a broader modulation response and the α-factor can be reduced by as much as 40%. The optical injection technique is attractive to improve the laser’s dynamical performance, including bandwidth enhancement and chirp reduction. These are demonstrated both theoretically and experimentally. The phase-amplitude coupling property is altered as well in comparison with the free-running laser and the optical gain depends on the injection strength and the frequency detuning. This work proposes a new method derived from the Hakki-Paoli method, enabling to measure the α-factor of semiconductor lasers under optical injection both below and above threshold. In addition, it is demonstrated theoretically that the α-factor in nanostructure lasers exhibits a threshold discontinuity, which is mainly attributed to the unclamped carrier populations in the off-resonant states. It is a fundamental limitation, preventing the reduction of the α-factor towards zero. Quantum cascade (QC) lasers rely on intersubband electronic transitions in multi-quantum well heterostructures. QC lasers show flat broadband AM response (tens of GHz) without resonance, which constitutes promising features for free-space communications. Surprisingly, calculations show that the QC laser exhibits an ultrabroad FM bandwidth on the order of tens of THz, about three orders of magnitude larger than the AM bandwidth. Optically injection-locked QC lasers also exhibit specific characteristics by comparison to interband semiconductor lasers. Both positive and negative frequency detunings enhance the modulation bandwidth
Chassagneux, Yannick. "Photonique pour les lasers à cascade quantique térahertz". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00740111.
Pełny tekst źródłaCharlton, Christy. "Quantum Cascade Lasers for Mid-Infrared Chemical Sensing". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/13953.
Pełny tekst źródłaBai, Jing. "Optimization of Optical Nonlinearities in Quantum Cascade Lasers". Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19797.
Pełny tekst źródłaSoulby, Michael Richard. "Mid-infrared spectroscopic studies of quantum cascade lasers". Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527223.
Pełny tekst źródłaQin, Qi Ph D. Massachusetts Institute of Technology. "Development of tunable terahertz quantum cascade wire lasers". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78548.
Pełny tekst źródłaCataloged from PDF version of thesis.
Includes bibliographical references (p. 179-188).
For a long time, terahertz (THz) radiation has been of great interest to scientific community because of its spectroscopic and imaging applications based on its unique properties, such as the capabilities to penetrate many materials which are opaque in other frequency range (e.g. packaging, plastics, paints and semiconductors), and spectroscopic signatures of many important materials. In this thesis, a continuously tunable THz wire QC laser, which comprises a QC laser with deep sub-wavelength transverse dimensions, and a movable side object, termed as "plunger", is demonstrated. This deep sub-wavelength cross-section results in a large fraction of mode propagating outside of the laser core (GaAs/A1₀.₁₅Ga₀.₈₅As material system). The frequency tuning is achieved by changing the transverse wave vector, using a plunger made by metal (metal plunger) or silicon (dielectric plunger). When nudged close to the wire laser core, the metal plunger can push modes to the opposite side of the waveguide. Confined by a metal-metal waveguide, the mode is squeezed and the transverse wave vector is increased, resulting in a blue-shifted frequency. In contrast, a silicon plunger can suck the mode out due to its similar refractive index to GaAs/Al₀.₁₅Ga₀.₈₅As material system of laser core. Thus a decreased transverse wave vector results in a redshifted frequency. Although a tuning record of 138GHz (3.6%) was achieved, a discontinuous tuning resulted from a jittering movement of the plungers due to its friction with the guiding system. To solve this problem, an improved plunger based on micro-mechanical system (MEMS) was implemented. This MEMS plunger uses a two-stage folded-beam flexure to isolate the misaligned external actuation. The plunger is attached with the flexure which suspends above a silicon substrate to eliminate friction. Eventually, this MEMS flexure was actuated by a mechanical system which comprised a lever to de-amplify the displacement of a linear mechanical feedthrough. This MEMS plunger enabled a restorable and frictionless movement which led to a continuous tuning range of 330GHz (8.6%) centered at ~3.85 THz. The challenges posted by the weak mode discrimination led to the development of comb-shape connectors which electrically connect the top metal of wire lasers and the side bonding pad. This design can significantly increase the mode discrimination by selectively guiding undesired mode into the lossy bonding pad. This robust design of single mode operation enables the initial lasing at a frequency far below the gain peak, which can potentially increase the tuning range significantly.
by Qi Qin.
Ph.D.
Atkins, Chris. "New developments in GaAs-based quantum cascade lasers". Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/5105/.
Pełny tekst źródłaWang, Feihu. "Ultrafast terahertz pulse generation from quantum cascade lasers". Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066752.
Pełny tekst źródłaTHz quantum cascade lasers (QCLs) are foundational semiconductor devices for laser action in the THz range. Considerable developments have been made in the last decade in terms of temperature operation and high output power. THz QCLs can also possess extremely large spectral bandwidths, rendering them suitable for ultrashort THz pulse generation through modelocking, with pulse widths of a few picoseconds theoretically obtainable. However, to date, the generation of THz pulses from QCLs has been limited to 10 - 20 ps, despite several years of research effort. In this thesis, this bottleneck in QCL technology is investigated and overcome. Several milestones have been achieved that permitted the realization of ultrashort pulse generation from QCLs. Current state-of-the-art performances are shown, using narrow spectral bandwidth QCLs in single-plasmon waveguides, and where modelocking results in 20 ps long THz pulses at low temperatures (10K). This is followed by, for the first time, mode-locking of broad spectral bandwidth QCLs in sub-wavelength metal-metal waveguides at ‘high’ temperatures (77K). Even with large spectral bandwidths, the shortest pulses achieved were only 11 ps and we show that the index dispersion and the electrical modulation are the critical factors. Finally, these effects are compensated through a Gires-Tournois interferometer and an extra loss mechanism, respectively, integrated monolithically onto a QCL. This approach permits to generate pulses as short as 4 ps, with the potential to go considerably further to the sub-picosecond or single cycle regime
Vaitiekus, Deivis. "Development of quantum cascade lasers for gas sensing applications". Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/13916/.
Pełny tekst źródłaMohd, Ibrahim Mohamed Shahrizan bin. "Segmented and patterned single-metal terahertz quantum cascade lasers". Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.545707.
Pełny tekst źródłaLaffaille, Pierre. "Lasers à cascade quantique moyen infrarouge à base d'InAs". Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-01021281.
Pełny tekst źródłaLeuliet, Aude. "Simulation du transport dans les lasers à cascade quantique". Paris 7, 2010. http://www.theses.fr/2010PA077070.
Pełny tekst źródłaQuantum cascade lasers (QCLs) are unipolar semiconductor devices based on the electronic transitions in the conduction band of a multiple quantum wells Systems and on resonant tunnelling. They are the only coherent semiconducting sources in the mid infrared to allow ambient temperature operation. The thesis aims at calculating the current in QCLs. After a short introduction on QCLs, the thesis is divided into 3 parts. The first part details the different diffusion processes taking place in the active region and determines which are the most important processes. The second part contains a study of QCLs under strong magnetic fields (up to 45 Teslas). This allow a more precise determination of processes taking place in the active region. The last part describes the calculation of the current in the QCL, based on the diffusion determined in the first chapters
Storck, Joakim. "A Measurement Platform for Characterization of Quantum Cascade Lasers". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191097.
Pełny tekst źródłaEn mätplattform har konstruerats för att karaktärisera kvantkaskadlasrar som återodlats på KTH genom att mäta deras spektrala och elektriska egenskaper vid rumstemperatur. Strömkällan som användes i detta arbete hade en spänningsgräns som var för låg för att kunna driva en kvantkaskadlaser över tröskeln. Därför byggdes en adapter för att sätta en extern spänningskälla i serie med denna och därmed höja spänningen över lasern. Adaptern simulerades först i OrCAD PSPICE och löddes sedan ihop och monterades i en plastlåda med kontakter för ström- och spänningskälla samt laserfästet. Automationsmjukvara gjordes i LabView för att automatisera den elektriska karaktäriseringen. Den ökar gradvis strömmen över ett definierat intervall och mäter ström och spänning över lasern samt dess optiska uteffekt och sparar alla data i en fil. Plattformen testades på ett en laserchip lånat från III-V Lab i Frankrike. Laserns L-I-V-kurva och spektrum mättes vid olika uteffekter och temperaturnivåer. Från L-I-V-kurvorna kunde verkningsgraden η och strömmens tröskelvärde Ith bestämmas och användas för att räkna ut de karakteristiska temperaturerna T0 = 40K och T1 = 10K. Detta resultat ledde till slutsatsen att antingen var lasern skadad eller så fungerade värmeledningen bort från lasern dåligt. Typiska värden på dessa temperaturer är i storleksordningen 200K. En kvalitativ analys gjordes av de spektrala mätresulteten, vilken indikerade en liten ökning av modernas våglängder och även modhopp till moder med längre våglängd vid ökning av temperaturen. Lasern var enkelmod men blev instabilare ju mer effekten eller temperaturen eller båda två ökade. Instabilt multimodbeteende sågs vid en uteffekt på 60mW vid 20oC. Efter mätningar och analyser framlades förslag på möjliga framtida förbättringar av plattformen.
Alhathlool, Raed Hussain S. "The development and applications of terahertz quantum cascade lasers". Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/6421/.
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