Download or read book Ultrafast Mid Infrared Dynamics in Quantum Cascade Lasers written by and published by . This book was released on 2010 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the entire research period. In this program, we performed experiments using a femtosecond mid-infrared pump-probe system implemented for QCL samples operating at 4.6 and 5.3 m. We employed femtosecond time-resolved pump-probe measurements to probe the nature of the transport through the laser structure via the dynamics of the gain. The gain recovery was determined by the time-dependent transport of electrons through the cascade heterostructure; as the laser approaches and exceeds threshold, the gain recovery shows a dramatic reduction due to the onset of quantum stimulated emission. Since the electron transport through each state in the cascade is determined by the state lifetime, the transport in a cascade laser is driven by the photon density in the cavity. The gain recovery is qualitatively different from that in conventional atomic, molecular and interband semiconductor lasers due to the superlattice transport in the cascade. We also studied the effects of pulse propagation in the laser, including group velocity dispersion and coherent pulse reshaping due to ultrafast Rabi flopping of the gain medium.
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 Ultrafast Dynamics in Quantum Cascade Lasers written by Hyunyong Choi and published by . This book was released on 2007 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mid infrared Quantum Cascade Lasers for Chaos Secure Communications written by Olivier Spitz and published by Springer. This book was released on 2022-05-17 with total page 166 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 Quantum Cascade Lasers written by Jérôme Faist and published by Oxford University Press. This book was released on 2013-03-14 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the physics, fabrication technology, and applications of the quantum cascade laser.
Download or read book Ultrafast Phenomena in Semiconductors written by Kong-Thon Tsen and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 513 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are many books in the market devoted to the review of certain fields. This book is different from those in that authors not only provide reviews of the fields but also present their own important contributions to the fields in a tutorial way. As a result, researchers who are already in the field of ultrafast dynamics in semicon ductors and its device applications as well as researchers and graduate students just entering the field will benefit from it. This book is made up of recent new developments in the field of ultrafast dynamics in semiconductors. It consists of nine chapters. Chapter 1 reviews a mi croscopic many-body theory which allows one to compute the linear and non-linear optical properties of semiconductor superlattices in the presence of homogeneous electric fields. Chapter 2 deals with ultrafast intersubband dynamics in quantum wells and device structures. Chapter 3 is devoted to Bloch oscillations in semicon ductors and their applications. Chapter 4 discusses transient electron transport phe nomena, such as electron ballistic transport and electron velocity overshoot phe nomena as well as non-equilibrium phonon dynamics in nanostructure semicon ductors. Chapter 5 reviews experimental and theoretical work on the use of the phase properties of one or more ultrashort optical pulses to generate and control electrical currents in semiconductors.
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 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 Optical Measurement on Quantum Cascade Lasers Using Femtosecond Pulses written by Hong Cai and published by . This book was released on 2014 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum cascade lasers (QCLs) as the state-of-the-art mid-infrared (mid-IR) coherent sources have been greatly developed in aspects such as output power, energy efficiency and spectral purity. However, there are additional applications of QCLs in high demand, namely mode-locking, mid-IR modulation, etc. The inherent optical properties and ultrafast carrier dynamics can lead to solutions to these challenges. In this dissertation, we further characterize QCLs using mid-IR femtosecond (fs) pulses generated from a laser system consisting of a Ti:sapphire oscillator, a Ti:sapphire regenerative amplifier, an optical parametric amplifier and a difference frequency generator.
Download or read book A New Generation of Ultrafast Oscillators for Mid Infrared Applications written by Nathalie Nagl and published by Springer Nature. This book was released on 2022-02-01 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the first successful realization of a compact, low-noise, and few-cycle light source in the mid-infrared wavelength region. By developing the technology of pumping femtosecond chromium-doped II-VI laser oscillators directly with the emission of broad-stripe single-emitter laser diodes, coherent light was generated with exceptionally low amplitude noise — crucial for numerous applications including spectroscopy at high sensitivities. Other key parameters of the oscillator's output, such as pulse duration and output power, matched and even surpassed previous state-of-the-art systems. As a demonstration of its unique capabilities, the oscillator's powerful output was used to drive — without further amplification — the nonlinear generation of coherent mid-infrared light spanning multiple octaves. The resulting table-top system uniquely combines high brilliance and ultrabroad spectral bandwidth in the important mid-infrared spectral range. The rapid development of this technology is comprehensively and lucidly documented in this PhD thesis. Together with a thorough review of literature and applications, and an extensive analysis of the theoretical foundations behind ultrafast laser oscillators, the thesis will serve as a valuable reference for the construction of a new generation of mid-infrared light sources.
Download or read book Mid infrared Spectroscopic Studies of Quantum Cascade Lasers written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optogenetic Tools in the Molecular Spotlight written by Tilo Mathes and published by Frontiers Media SA. This book was released on 2016-08-09 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rise of optogenetics as a standard technique to non-invasively probe and monitor biological function created an immense interest in the molecular function of photosensory proteins. These photoreceptors are usually protein/pigment complexes that translate light into biological information and have become essential tools in cell biology and neurobiology as their function is genetically encoded and can be conveniently delivered into a given cell. Like for fluorescent proteins that quickly became invaluable as genetically encodable reporters in microscopy and imaging, variants of photosensory proteins with customized sensitivity and functionality are nowadays in high demand. In this ebook we feature reviews and original research on molecular approaches from synthetic biology and molecular spectroscopy to computational molecular modelling that all aspire to elucidate the molecular prerequisites for the photosensory function of the given proteins. The principle property of changing activity of biological function simply by application of light is not only very attractive for cell biology, it also offers unique opportunities for molecular studies as excitation can be controlled with high time precision. Especially in spectroscopy the usually fully reversible photoactivation of photosensory proteins allows researchers to to perform time resolved studies with up to femtosecond resolution. In addition, functional variants can be investigated and quickly screened in common biochemical experiments. The insights that are obtained by the here presented various yet complementary methods will ultimately allow us write the script for a molecular movie from excitation of the protein by a photon to activation of its biological function. Such deep understanding does not only provide unique insights into the dynamics of protein function, it will also ultimately enable us to rationally design novel optogenetic tools to be used in cell biology and therapy.
Download or read book Terahertz and Mid Infrared Radiation written by Mauro Pereira and published by Springer Science & Business Media. This book was released on 2011-02-26 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Terahertz (THz) and Mid-Infrared (MIR) radiation (TERA-MIR) can be transmitted through nearly any material without causing biological harm. Novel and rapid methods of detection can be created with devices operation in these spectral ranges allowing scanning for weapons, detecting hidden explosives (including plastic landmines), controlling the quality of food and a host of other exciting applications. This book focuses on mathematical and physical aspects of the field, on unifying these two spectral domains (THz and MIR) with regard to common sources, detectors, materials and applications, and on key interdisciplinary topics. The main THz and MIR source is the quantum cascade laser (QCL). Thus significant attention is paid to the challenge of turning this advanced technology into affordable commercial devices so as to exploit its enormous potential. However other alternatives to THz QCLs are also presented, e.g. sub-terahertz imaging from avalanching GaAs bipolar transistors, Josephson junctions as THz sources, semiconductor materials for pulsed THz sources, superconducting THz electronics with Josephson vortices. In summary this book delivers a global picture of the state of the art in TERA-MIR generation, detection and applications.
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 Multimode Dynamics in Quantum Cascade Lasers written by Christine Yi-Ting Wang and published by . This book was released on 2008 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main experimental signature of RNGH instability is a splitting corresponding to twice the Rabi frequency in optical spectrum. In QCLs this coherent instability is enhanced due to the large Rabi frequency compared to the relaxation rates. We have also shown that spatial hole burning, which is not so readily observable in diode lasers, also plays an important role in QCLs. Both experimental data and simulations based on Maxwell-Bloch equations are presented. In the second part of this thesis, we demonstrate active mode-locking in QCLs. The stable mode-locked pulse train was generated by actively modulating the pumping current of a small section on a QCL. Stable mode locking was confirmed by second-order interferometric autocorrelation measurements, and a FWHM of 3 ps and about 0.5 pJ per pulse were deduced from the autocorrelation traces. The system is also simulated using Maxwell-Bloch equations incorporated with a modulation term. We anticipate our results to be a big step toward a compact, electrically-pumped source generating ultrashort pulses in the mid-infrared and terahertz ranges.
Download or read book Investigation of Carrier Dynamics and Nonlinear Effects in Quantum Cascade Lasers Using Femtosecond Mid IR Pulses written by Sheng Liu and published by . This book was released on 2011 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ultrafast Phenomena XII written by T. Elsaesser and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 709 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the latest advances in ultrafast science, including ultrafast laser and measurement technology, and studies of ultrafast phenomena. It summarizes the results presented at the 12th Ultrafast Phenomena Conference and reviews the state of the art of this important and rapidly advancing field.
