Download or read book Analysis and Improvement of the Spectral Properties in Mid infrared Semiconductor Quantum Cascade Lasers written by Lionel Tombez and published by . This book was released on 2014 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonlinear Photonics in Mid infrared Quantum Cascade Lasers written by Louise Jumpertz and published by Springer. This book was released on 2017-08-31 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the first comprehensive analysis of quantum cascade laser nonlinear dynamics and includes the first observation of a temporal chaotic behavior in quantum cascade lasers. It also provides the first analysis of optical instabilities in the mid-infrared range. Mid-infrared quantum cascade lasers are unipolar semiconductor lasers, which have become widely used in applications such as gas spectroscopy, free-space communications or optical countermeasures. Applying external perturbations such as optical feedback or optical injection leads to a strong modification of the quantum cascade laser properties. Optical feedback impacts the static properties of mid-infrared Fabry–Perot and distributed feedback quantum cascade lasers, inducing power increase; threshold reduction; modification of the optical spectrum, which can become either single- or multimode; and enhanced beam quality in broad-area transverse multimode lasers. It also leads to a different dynamical behavior, and a quantum cascade laser subject to optical feedback can oscillate periodically or even become chaotic. A quantum cascade laser under external control could therefore be a source with enhanced properties for the usual mid-infrared applications, but could also address new applications such as tunable photonic oscillators, extreme events generators, chaotic Light Detection and Ranging (LIDAR), chaos-based secured communications or unpredictable countermeasures.
Download or read book Mid Infrared Quantum Cascade Lasers written by Alfredo Bismuto and published by LAP Lambert Academic Publishing. This book was released on 2012-02 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work describes the work performed by the author at the ETH Zurich, under the supervision of Prof. Jerome Faist on the optimization of high performance quantum cascade lasers (QCLs) in the Mid-IR spectral region. The main factors influencing laser performance have therefore been analyzed. In particular the optimization of the laser design in order to improve the electron tranport and the optical gain. In addition a detailed analysis of the fabrication process is performed and a novel process scheme is presented for buried heterostructure lasers.
Download or read book Mid infrared Quantum Cascade Lasers for Chaos Secure Communications written by Olivier Spitz and published by Springer Nature. This book was released on 2021-05-15 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mid-infrared domain is a promising optical domain because it holds two transparency atmospheric windows, as well as the fingerprint of many chemical compounds. Quantum cascade lasers (QCLs) are one of the available sources in this domain and have already been proven useful for spectroscopic applications and free-space communications. This thesis demonstrates how to implement a private free-space communication relying on mid-infrared optical chaos and this requires an accurate cartography of non-linear phenomena in quantum cascade lasers. This private transmission is made possible by the chaos synchronization of two twin QCLs. Chaos in QCLs can be generated under optical injection or external optical feedback. Depending on the parameters of the optical feedback, QCLs can exhibit several non-linear phenomena in addition to chaos. Similarities exist between QCLs and laser diodes when the chaotic dropouts are synchronized with an external modulation, and this effect is known as the entrainment phenomenon. With a cross-polarization reinjection technique, QCLs can generate all-optical square-waves. Eventually, it is possible to trigger optical extreme events in QCLs with tilted optical feedback. All these experimental results allow a better understanding of the non-linear dynamics of QCLs and will extend the potential applications of this kind of semiconductor lasers.
Download or read book Spectral Characterization of a Mid infrared Quantum cascade Laser written by Nathan E. Rines and published by . This book was released on 2006 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mid Infrared and Terahertz Quantum Cascade Lasers written by Dan Botez and published by Cambridge University Press. This book was released on 2023-09-14 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn how the rapidly expanding area of mid-infrared and terahertz photonics has been revolutionized in this comprehensive overview. State-of-the-art practical applications are supported by real-life examples and expert guidance. Also featuring fundamental theory enabling you to improve performance of both existing and future devices.
Download or read book Quantum Cascade Lasers and Optical Metamaterials written by Matthew Escarra and published by LAP Lambert Academic Publishing. This book was released on 2013-01 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum cascade (QC) lasers have application in areas such as medical diagnostics and homeland security. Optical metamaterials have novel interactions with light and potential application for sub-wavelength imaging and optical cloaking. This work first explores new approaches to designing QC lasers. High performance QC lasers are described with a voltage defect of only 19 meV, resulting in record voltage efficiency. Lasers with ultra-strong coupling attain 50% wall-plug efficiency. The thermoelectric effect is measured for the first time within QC lasers, informing further performance enhancements. This work then describes two efforts to improve mid-IR metamaterials. Negative refraction bandwidth and dispersion properties are improved through the use of multiple-metamaterial stacks. QC gain regions are added to these metamaterials to reduce their absorption loss. Finally, QC lasers are developed for trace gas sensing of CO2 isotopes, and a techno-economic model is used to value improved CO2 isotope-based sequestration leakage monitoring. QC laser applications in non-invasive tissue measurements, inter-planetary sensors, C60 spectroscopy, and IR countermeasures are also examined.
Download or read book Spectroscopic Applications of Terahertz Quantum Cascade Lasers written by Tasmim Alam and published by Cuvillier Verlag. This book was released on 2020-10-29 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum cascade lasers (QCLs) are attractive for high-resolution spectroscopy because they can provide high power and a narrow linewidth. They are particularly promising in the terahertz (THz) range since they can be used as local oscillators for heterodyne detection as well as transmitters for direct detection. However, THz QCL-based technologies are still under development and are limited by the lack of frequency tunability as well as the frequency and output power stability for free-running operation. In this dissertation, frequency tuning and linewidth of THz QCLs are studied in detail by using rotational spectroscopic features of molecular species. In molecular spectroscopy, the Doppler eff ect broadens the spectral lines of molecules in the gas phase at thermal equilibrium. Saturated absorption spectroscopy has been performed that allows for sub-Doppler resolution of the spectral features. One possible application is QCL frequency stabilization based on the Lamb dip. Since the tunability of the emission frequency is an essential requirement to use THz QCL for high-resolution spectroscopy, a new method has been developed that relies on near-infrared (NIR) optical excitation of the QCL rear-facet. A wide tuning range has been achieved by using this approach. The scheme is straightforward to implement, and the approach can be readily applied to a large class of THz QCLs. The frequency and output stability of the local oscillator has a direct impact on the performance and consistency of the heterodyne spectroscopy. A technique has been developed for a simultaneous stabilization of the frequency and output power by taking advantage of the frequency and power regulation by NIR excitation. The results presented in this thesis will enable the routine use of THz QCLs for spectroscopic applications in the near future.
Download or read book Quantum Cascade Lasers written by Jérôme Faist and published by OUP Oxford. This book was released on 2013-03-14 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an introduction to quantum cascade lasers, including the basic underlying models used to describe the device. It aims at giving a synthetic view of the topic including the aspects of the physics, the technology, and the use of the device. It should also provide a guide for the application engineer to use this device in systems. The book is based on lecture notes of a class given for Masters and beginning PhD students. The idea is to provide an introduction to the new and exciting developments that intersubband transitions have brought to the use of the mid-infrared and terahertz region of the electromagnetic spectrum. The book provides an introductory part to each topic so that it can be used in a self-contained way, while references to the literature will allow deeper studies for further research.
Download or read book Dairy Chemistry and Biochemistry written by P. F. Fox and published by Springer. This book was released on 2015-06-19 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the most comprehensive introductory text on the chemistry and biochemistry of milk. It provides a comprehensive description of the principal constituents of milk (water, lipids, proteins, lactose, salts, vitamins, indigenous enzymes) and of the chemical aspects of cheese and fermented milks and of various dairy processing operations. It also covers heat-induced changes in milk, the use of exogenous enzymes in dairy processing, principal physical properties of milk, bioactive compounds in milk and comparison of milk of different species. This book is designed to meet the needs of senior students and dairy scientists in general.
Download or read book Infrared Spectroscopy written by Barbara H. Stuart and published by John Wiley & Sons. This book was released on 2004-08-20 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an introduction to those needing to use infrared spectroscopy for the first time, explaining the fundamental aspects of this technique, how to obtain a spectrum and how to analyse infrared data covering a wide range of applications. Includes instrumental and sampling techniques Covers biological and industrial applications Includes suitable questions and problems in each chapter to assist in the analysis and interpretation of representative infrared spectra Part of the ANTS (Analytical Techniques in the Sciences) Series.
Download or read book Optical and Thermal Properties of InP based Mid infrared Quantum Cascade Lasers written by and published by . This book was released on 2007 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum Cascade Lasers Based on Intra cavity Frequency Mixing written by Min Jang and published by . This book was released on 2012 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum cascade lasers (QCLs) operate due to population inversion on intersubband in unipolar mutiple-quantum-well (MQW) heterostructure. QCLs are considered one of the most flexible and powerful light semiconductor sources in the mid- and far-infrared (IR) wavelength range, covering most of the critical spectral regions relevant to IR applications. InGaAs/InAlAs/InP QCLs are the only semiconductor lasers capable of continuous wave (CW) operation at room temperature (RT) in the spectral range 3.4-12 micron. This dissertation details the development of RT QCLs based on passive nonlinear coupled-quantum-well structures monolithically integrated into mid-IR QCLs to provide a giant nonlinear response for the pumping frequency. The primary focus of short-wavelength approach in this dissertation is to develop of RT InGaAs/InAlAs/InP QCLs for lamda=2.5-3.7 micron region, based on quasi-phase-matched intracavity second harmonic generation (SHG) associated with intersubband transition. Intersubband optical transition can be engineered by the choice of quantum well and barrier thicknesses to provide the appropriate energy levels, optical dipole matrix elements, and electron scattering rates amongst other parameters. Thus, aside from their linear optical properties, resonant intersubband transitions in coupled QW's can also be designed to produce nonlinear optical medium with giant nonlinear optical susceptibilities. In long-wavelength region, at high temperature, the population inversion is reduced between the upper and lower laser levels due to the longitudinal optical (LO) phonon scattering of thermal carriers in the upper laser state and the thermal backfilling of carriers into the lower laser level from the injector state. This dissertation aims to improve an alternative approach for THz QCL sources based on intra-cavity difference frequency generation (DFG) in dual-wavelength mid-IR QCLs with a passive nonlinear structure, designed for giant optical nonlinearity. Further studies describe that Cerenkov DFG scheme allows for extraction of THz radiation along the whole length of the laser waveguide and provides directional THz emission in 1.2-4.5 THz range. An important requirement for many applications, like chemical sensing and molecular spectroscopy, is single-mode emission. We demonstrate single-mode RT DFG THz QCLs operation in 1-5 THz region by employing devices as integrated dual-period DFB lasers, where efficient solid state RT sources do not exist.
Download or read book Advances in Spectroscopic Monitoring of the Atmosphere written by Weidong Chen and published by Elsevier. This book was released on 2021-06-09 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Spectroscopic Monitoring of the Atmosphere provides a comprehensive overview of cutting-edge technologies and monitoring applications. Concepts are illustrated by numerous examples with information on spectroscopic techniques and applications widely distributed throughout the text. This information is important for researchers to gain an overview of recent developments in the field and make informed selections among the most suitable techniques. This volume also provides information that will allow researchers to explore implementing and developing new diagnostic tools or new approaches for trace gas and aerosol sensing themselves. Advances in Spectroscopic Monitoring of the Atmosphere covers advanced and newly emerging spectroscopic techniques for optical metrology of gases and particles in the atmosphere. This book will be a valuable reference for atmospheric scientists, including those whose focus is applying the methods to atmospheric studies, and those who develop instrumentation. It will also serve as a useful introduction to researchers entering the field and provide relevant examples to researchers and students developing and applying optical sensors for a variety of other scientific, technical, and industrial uses. Overview of new applications including remote sensing by UAV, laser heterodyne radiometry, dual comb spectroscopy, and more Features in-situ observations and measurements for real-world data Includes content on leading edge optical sensors
Download or read book Design Analysis and Characterization of Indirectly pumped Terahertz Quantum Cascade Lasers written by Seyed Ghasem Razavipour and published by . This book was released on 2013 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum cascade laser (QCL), as a unipolar semiconductor laser based on intersubband transitions in quantum wells, covers a large portion of the Mid and Far Infrared electromagnetic spectrum. The frequency of the optical transition can be determined by engineering the layer sequence of the heterostructure. The focus of this work is on Terahertz (THz) frequency range (frequency of 1 - 10 THz and photon energy of ~ 4 - 40 meV), which is lacking of high power, coherent, and efficient narrowband radiation sources. THz QCL, demonstrated in 2002, as a perfect candidate of coherent THz source, is still suffering from the empirical operating temperature limiting factor of T [ap] h̳[omega]/kB, which allows this source to work only under a cryogenic system. Most of high performance THz QCLs, including the world record design which lased up to ~ 200 K, are based on a resonant phonon (RP) scheme, whose population inversion is always less than 50%. The indirectly-pumped (IDP) QCL, nicely implemented in MIR frequency, starts to be a good candidate to overcome the aforementioned limiting factor of RP-QCL. A rate equation (RE) formalism, which includes both coherent and incoherent transport process, will be introduced to model the carrier transport of all presented structures in this thesis. The second order tunneling which employed the intrasubband roughness and impurity scattering, was implemented in our model to nicely predict the behavior of the QCL designs. This model, which is easy to implement and fast to calculate, could help us to engineer the electron wavefunctions of the structure with optimization tools. We developed a new design scheme which employs the phonon scattering mechanism for both injecting carrier to the upper lasing state and extracting carrier from lower lasing state. Since there is no injection/extraction state to be in resonance with lasing states, this simple design scheme does not suffer from broadening due to the tunneling. Finally, three different THz IDP-QCLs, based on phonon-photon-phonon (3P) scheme were designed, grown, fabricated, and characterized. The performance of those structures in terms of operating temperature, threshold current density, maximum current density, output optical power, lasing frequency, differential resistance at threshold, intermediate resonant current before threshold, and kBT/h̳[omega] factor will be compared. We could improve the kBT/h̳[omega] factor of the 3P-QCL design from 0.9 in first iteration to 1.3 and the output optical power of the structure from 0.9 mW in first design to 3.4 mW. The performance of the structure in terms of intermediate resonant current and the change in differential resistance at threshold was improved.
Download or read book Broadly Tunable Mid infrared Quantum Cascade Lasers for Spectroscopic Applications written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum cascade lasers are unipolar semiconductor lasers based on intersubband transitions in heterostructures. These lasers, which have demonstrated continuous wave operation at room temperature in the mid-infrared spectral range, are well suited for the realization of compact, ultra-sensitive, trace-gas sensors based on absorption spectroscopy. Up to now, only distributed feedback (DFB) single-mode devices have been used for such applications. DFB quantum cascade lasers have proven to be effective for gas sensing, but their relatively narrow tuning range, smaller or equal to about 1% of the wavelength, makes them not very versatile and limits their usefulness for spectroscopic investigations. In this thesis we developed broadly tunable external cavity quantum cascade lasers. The main advantage of these sources compared with DFBs is their broader tuning range, which is limited only by the spectral bandwidth of the gain element. We particularly studied broad gain bandwidth active regions based on bound-to-continuum designs. With that kind of active region, we have demonstrated a tuning range equal to 15% of the center wavelength at l ~ 10 mm, which was three times broader than the best values reported in the literature at that time, as well as good performance in pulsed mode at room temperature. Using a strain-compensated bound-to-continuum design emitting near 5.2 mm, we have demonstrated for the first time continuous-wave operation of an external cavity quantum cascade laser on a thermoelectric cooler. The tuning range was comparable to that of pulsed devices, but with a much better side-mode suppression ratio and a much narrower linewidth. This continuous-wave device has successfully been applied to the spectroscopy of nitric oxide in collaboration with Prof. Tittel's Laser Science Group at Rice University. High resolution absorption spectra of that gas could be acquired over a large wavelength range. We also studied heterogeneous cascade structures, that is quan.
Download or read book INTERNAL REFLECTION SPECTROSCOPY written by N. J. Harrick and published by . This book was released on 1967 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
