Epitaxial Design Optimizations For Increased Efficiency In Gaas Based High Power Diode Lasers
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Epitaxial Design Optimizations For Increased Efficiency In Gaas Based High Power Diode Lasers
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Author : Thorben Kaul
language : en
Publisher: Cuvillier Verlag
Release Date : 2021-04-09
Epitaxial Design Optimizations For Increased Efficiency In Gaas Based High Power Diode Lasers written by Thorben Kaul and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-04-09 with Science categories.
This work presents progress in the root-cause analysis of power saturation mechanisms in continuous wave (CW) driven GaAs-based high-power broad area diode lasers operated at 935 nm. Target is to increase efficiency at high optical CW powers by epitaxial design. The novel extreme triple asymmetric (ETAS) design was developed and patented within this work to equip diode lasers that use an extremely thin p-waveguide with a high modal gain. An iterative variation of diode lasers employing ETAS designs was used to experimentally clarify the impact of modal gain on the temperature dependence of internal differential quantum efficiency (IDQE) and optical loss. High modal gain leads to increased free carrier absorption from the active region. However, less power saturation is observed, which must then be attributed to an improved temperature sensitivity of the IDQE. The effect of longitudinal spatial hole burning (LSHB) leads to above average non-linear carrier loss at the back facet of the device. At high CW currents the junction temperature rises. Therefore, not only the asymmetry of the carrier profile increases but also the average carrier density in order to compensate for the decreased material gain and increased threshold gain. This carrier non-pinning effect above threshold is found in this work to enhance the impact of LSHB already at low currents, leading to rapid degradation of IDQE with temperature. This finding puts LSHB into a new context for CW-driven devices as it emphasizes the importance of low carrier densities at threshold. The carrier density was effectively reduced by applying the novel ETAS design. This enabled diode lasers to be realized that show minimized degradation of IDQE with temperature and therefore improved performance in CW operation.
Short Channel Gan Fet Mmic Technology For High Reliability Applications Band 74
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Author : Konstantin Osipov
language : en
Publisher: Cuvillier Verlag
Release Date : 2024-02-07
Short Channel Gan Fet Mmic Technology For High Reliability Applications Band 74 written by Konstantin Osipov and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-02-07 with categories.
Nowdays GaN HEMT technology reached maturity level that allows industral fabrication of such devices for wide range of civil (telecommunications, power electrinics, automotive etc.), as well as space and military (phased array radars) applications. At this level, technology start reaching physical limits of GaN material and require new approaches that will allow to overcome some of well known problems related to GaN HEMTs, such as high gate leakage currents, reliability issues and difficulties of normally-off transistor fabrication. The goal of these theses is theoretical and experimental confirmation of the idea, that using peizoelectric nature of GaN crystal will allow local modification of GaN HEMT channel by means of external mechanical stress (using first and second passivation layers as stressors). After implementation of the proposed technology changes and new device geometry in process flow intended for 150 nm GaN HEMTMMIC fabrication, E/D devices with pinch-off voltages +0.1V and -1.65V respectively were fabricated on the same wafer within single process flow. It was observed, that E-mode devices, fabricated using compressed passivation layers, demonstrate lower gate leakage currents and more robust in HTRB test as compared to D-mode devices. In summary, it was demonstrated, that it is possible to control pinch-off voltage and gate leakage current of short channel GaN HEMTs by application of external stress. Usage of external stress, opens new degree of freedom in device optimization, and extends opportunities for more advanced MMIC design.
Design Simulation And Analysis Of Laterally Longitudinally Non Uniform Edge Emitting Gaas Based Diode Lasers Band 73
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Author : Jan-Philipp Koester
language : en
Publisher: Cuvillier Verlag
Release Date : 2023-09-19
Design Simulation And Analysis Of Laterally Longitudinally Non Uniform Edge Emitting Gaas Based Diode Lasers Band 73 written by Jan-Philipp Koester and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-09-19 with categories.
Edge-emitting quantum-well diode lasers based on GaAs combine a high conversion efficiency, a wide range of emission wavelengths covering a span from 630 nm to 1180 nm, and the ability to achieve high output powers. The often used longitudinal-invariant Fabry-Pérot-type resonators are easy to design but often lead to functionality or performance limitations. In this work, the application of laterally-longitudinally non-uniform resonator configurations is explored as a way to reduce unwanted and performance-limiting effects. The investigations are carried out on existing and entirely newly developed laser designs using dedicated simulation tools. These include a sophisticated time-dependent laser simulator based on a traveling-wave model of the optical fields in the lateral-longitudinal plane and a Maxwell solver based on the eigenmode expansion method for the simulation of passive waveguides. Whenever possible, the simulation results are compared with experimental data. Based on this approach, three fundamentally different laser types are investigated: • Dual-wavelength lasers emitting two slightly detuned wavelengths around 784 nm out of a single aperture • Ridge-waveguide lasers with tapered waveguide and contact layouts that emit light of a wavelength of around 970 nm • Broad-area lasers with slightly tapered contact layouts emitting at 910 nm The results of this thesis underline the potential of lateral-longitudinal non-uniform laser designs to increase selected aspects of device performance, including beam quality, spectral stability, and output power.
High Power Diode Lasers
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Author : Roland Diehl
language : en
Publisher: Springer Science & Business Media
Release Date : 2003-07-01
High Power Diode Lasers written by Roland Diehl and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-07-01 with Science categories.
Methods of design and fabrication of high-power diode lasers using proven semiconductor technologies are described in this book. The latter include epitaxy and optical lithography, mounting on heat sinks, beam forming with micro-optics and coupling to optical fibers, and reliability testing. Direct applications of high-power diode lasers in materials processing and for pumping hitherto unknown solid-state laser systems are presented in a comprehensive fashion. Thus, this book is an invaluable source of information for all scientists and engineers designing laser systems and applying the laser as a reliable and economic tool in a multitude of environments.
Broad Area Laser Bars For 1 Kw Emission
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Author : Matthias M. Karow
language : en
Publisher: Cuvillier Verlag
Release Date : 2022-06-27
Broad Area Laser Bars For 1 Kw Emission written by Matthias M. Karow and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-06-27 with Technology & Engineering categories.
ndustrial laser systems for material processing applications rely on the availability of highly efficient, high-brightness diode lasers. GaAs-based broad-area laser bars play a vital role in such applications as pump sources for high-beam-quality solid-state lasers and, increasingly, as direct processing tools. This work studies 940 nm-laser bars emitting 1 kW optical power at room temperature, identifying those physical mechanisms that are currently limiting electrical-to-optical conversion efficiency as well as lateral beam quality. In the process, several diagnostic studies on bars with varied lateral-longitudinal design were carried out. The effects of technological measures for performance optimization were analyzed, yielding a new benchmark in efficiency and lateral divergence. The studies into altered resonator lengths of 4 and 6 mm as well as fill factors between 69 and 87 % successfully reduce both the voltage dropping across the device and power saturation at high currents, enabling 66 % efficiency at the operation point. Concrete measures how to reach efficiencies ≥70 % are presented thereafter, showing that doubling the efficiency value of the first 1 kW-demonstration in 2007 – amounting to 35 % – is in near reach. Investigation of the beam quality bases on a herein proposed and realized concept, in which the far field is resolved for each individual bar emitter. In this way, it is possible to determine how far-field profiles vary along the bar width and how much these variations affect the overall bar far-field. Further, such effects specific to bar structures can be separated into non-thermal and thermal influences. The effect of mechanical chip deformation (bar smile) as well as neighboring-emitter interaction has been investigated for the first time in active kW-class devices, yielding a lateral divergence as low as 8.8° at the operation point.
Istfa 2012
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Author : ASM International
language : en
Publisher: ASM International
Release Date : 2012
Istfa 2012 written by ASM International and has been published by ASM International this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Technology & Engineering categories.
Design And Realization Of Novel Gaas Based Laser Concepts
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Author : Tim David Germann
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-02-26
Design And Realization Of Novel Gaas Based Laser Concepts written by Tim David Germann and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-02-26 with Technology & Engineering categories.
Semiconductor heterostructures represent the backbone for an increasing variety of electronic and photonic devices, for applications including information storage, communication and material treatment, to name but a few. Novel structural and material concepts are needed in order to further push the performance limits of present devices and to open up new application areas. This thesis demonstrates how key performance characteristics of three completely different types of semiconductor lasers can be tailored using clever nanostructure design and epitaxial growth techniques. All aspects of laser fabrication are discussed, from design and growth of nanostructures using metal-organic vapor-phase epitaxy, to fabrication and characterization of complete devices.
Accge 2015 Abstracts Ebook
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Author : American Association for Crystal Growth (AACG)
language : en
Publisher: Coe Truman International, LLC
Release Date : 2015-07-15
Accge 2015 Abstracts Ebook written by American Association for Crystal Growth (AACG) and has been published by Coe Truman International, LLC this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-07-15 with Medical categories.
A collection of abstracts for the 20th American Conference on Crystal Growth and Epitaxy (ACCGE-20) and 17th U.S. Biennial Workshop on Organometallic Vapor Phase Epitaxy (OMVPE-17) and The Second 2D Electronic Materials Symposium.
Advanced Microwave And Millimeter Wave Technologies
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Author : Moumita Mukherjee
language : en
Publisher: BoD – Books on Demand
Release Date : 2010-03-01
Advanced Microwave And Millimeter Wave Technologies written by Moumita Mukherjee and has been published by BoD – Books on Demand this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-03-01 with Technology & Engineering categories.
This book is planned to publish with an objective to provide a state-of-the-art reference book in the areas of advanced microwave, MM-Wave and THz devices, antennas and systemtechnologies for microwave communication engineers, Scientists and post-graduate students of electrical and electronics engineering, applied physicists. This reference book is a collection of 30 Chapters characterized in 3 parts: Advanced Microwave and MM-wave devices, integrated microwave and MM-wave circuits and Antennas and advanced microwave computer techniques, focusing on simulation, theories and applications. This book provides a comprehensive overview of the components and devices used in microwave and MM-Wave circuits, including microwave transmission lines, resonators, filters, ferrite devices, solid state devices, transistor oscillators and amplifiers, directional couplers, microstripeline components, microwave detectors, mixers, converters and harmonic generators, and microwave solid-state switches, phase shifters and attenuators. Several applications area also discusses here, like consumer, industrial, biomedical, and chemical applications of microwave technology. It also covers microwave instrumentation and measurement, thermodynamics, and applications in navigation and radio communication.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1995-08
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995-08 with Aeronautics categories.