Epitaxial Design Optimizations for Increased Efficiency in GaAs-Based High Power Diode Lasers

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Publisher : Cuvillier Verlag
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Language : EN, FR, GB
ISBN 10 : 9783736963962
Pages : 136 pages
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Summary Book Review Epitaxial Design Optimizations for Increased Efficiency in GaAs-Based High Power Diode Lasers :

Download or read book Epitaxial Design Optimizations for Increased Efficiency in GaAs-Based High Power Diode Lasers written by Thorben Kaul and published by Cuvillier Verlag. This book was released on 2021-04-09 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Optimization of broad-area GaAs diode lasers for high powers and high efficiencies in the temperature range 200-220 K

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Publisher : Cuvillier Verlag
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ISBN 10 : 9783736989443
Pages : 174 pages
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Summary Book Review Optimization of broad-area GaAs diode lasers for high powers and high efficiencies in the temperature range 200-220 K :

Download or read book Optimization of broad-area GaAs diode lasers for high powers and high efficiencies in the temperature range 200-220 K written by Carlo Frevert and published by Cuvillier Verlag. This book was released on 2019-07-11 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work focuses on the development of AlGaAs-based diode laser (DL) bars optimized for reaching highest powers and efficiencies at low operation temperatures. Specifically, the quasi continuous wave (QCW) pumping of cryogenically cooled Yb:YAG solid-state lasers is targeted, setting requirements on the wavelength (940 nm), the pulse conditions (pulse length 1.2 ms) and frequency (10 Hz) as well as the lowest DL operating temperature THS ~ 200 K, consistent with economic cooling. High fill-factor bars for QCW operation are to reach high optical performance with optical output powers of P  1.5 kW and power conversion efficiencies of ŋE  60% at these power levels. Understanding the efficiency-limiting factors and the behavior at lower temperatures is necessary to design these devices. Optimizations are performed iteratively in three stages. First, vertical epitaxial designs are studied theoretically, adjusted to the targeted operation temperatures and specific laser parameters are extracted. Secondly, resulting vertical designs are processed into low power single emitters and their electro-optical behavior at low currents is experimentally assessed over a wide range of temperatures. The obtained laser parameters characteristic to the vertical design are then used to extrapolate the laser's performance up to the high targeted currents. Finally, vertical designs promising to reach the targeted values for power and efficiency are processed into high power single emitters and bars which are measured up to the highest currents. Eventually, laser bars are fabricated reaching output powers of 2 kW and efficiencies of 61% at 1.5 kW at an operation temperature of 203 K.

A deep ultraviolet laser light source by frequency doubling of GaN based external cavity diode laser radiation

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Publisher : Cuvillier Verlag
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ISBN 10 : 9783736966130
Pages : 130 pages
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Summary Book Review A deep ultraviolet laser light source by frequency doubling of GaN based external cavity diode laser radiation :

Download or read book A deep ultraviolet laser light source by frequency doubling of GaN based external cavity diode laser radiation written by Norman Ruhnke and published by Cuvillier Verlag. This book was released on 2022-05-13 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: A compact and portable laser light source emitting in the wavelength range between 210 nm and 230 nm would enable numerous applications outside of laboratory environments, such as sterilization and disinfection of medical equipment, water purification or gas and air analysis using absorption spectroscopy. Such a source is also highly attractive for the identification and quantification of proteins and biomolecules by means of laser-induced fluorescence or Raman spectroscopy. In this thesis, a novel concept to realize such a compact and portable laser light source with low power consumption and an emission around 222 nm is investigated. The developed concept is based on single-pass frequency doubling of a commercially available high-power GaN laser diode emitting in the blue spectral range. Due to the low frequency doubling conversion efficiencies in this wavelength range of about 10-4 W-1, a laser diode with high optical output power above 1 W is required as pump source. Moreover, it has to exhibit narrowband emission in the range of the acceptance bandwidth of the applied nonlinear BBO crystal. Since GaN-based high-power laser diodes typically show broad emission spectra of Δλ = 1…2 nm, stabilizing and narrowing their wavelength by using external wavelength-selective elements is investigated and presented for the first time. With the understanding for the novel concept gained in this work, a compact ultraviolet laser light source was realized. It has a power consumption of less than 10 W and is exceptionally robust due to its immoveable components. The demonstrated output power of 160 μW enables numerous industrial and everyday applications for which previous laser systems have been too complex and overly cost- and energy-intensive.

AlN base layers for UV LEDs

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Publisher : Cuvillier Verlag
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ISBN 10 : 9783736964518
Pages : 156 pages
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Summary Book Review AlN base layers for UV LEDs :

Download or read book AlN base layers for UV LEDs written by Sebastian Walde and published by Cuvillier Verlag. This book was released on 2021-06-22 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: To enable the fabrication of high performance ultraviolet (UV) light-emitting diodes (LEDs) this work aims at improving the quality of AlN base layers on sapphire substrates. The main issues for UV LEDs are still a limited internal quantum efficiency due to a high amount of threading dislocations along with a limited light extraction efficiency due to total internal reflection at the AlN/sapphire interface. Therefore, high-temperature annealing of AlN/sapphire layers and growth on nanopatterned sapphire substrates were comprehensively investigated. High-temperature annealing was applied to AlN layers of different strain and thickness grown by metalorganic vapour phase epitaxy (MOVPE). The threading dislocation density could be successfully reduced by more than one order of magnitude down to 6 × 108 cm-2. Wave optical simulations of UV LEDs on nanopatterned sapphire substrates (NPSS) were conducted and showed a potential increase in light extraction efficiency compared to a planar substrate. The optimized MOVPE growth process on sapphire nanopillars and sapphire nanoholes resulted in a fully coalesced and atomically smooth AlN surface. The threading dislocation density was reduced to 1 ×109 cm-2 for AlN on both nanopillars and nanoholes. UVC LEDs emitting at 265 nm wavelength were grown on top of the developed templates. Increased internal efficiency was obtained by reduced dislocation density and more efficient light extraction was achieved on NPSS in case of a transparent heterostructure and reflective contacts. Thus, the developed templates yield considerable improvement in light output compared to conventional templates.

ACCGE 2015 Abstracts eBook

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Publisher : Coe Truman International, LLC
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Language : EN, FR, GB
ISBN 10 : 9781613300084
Pages : pages
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Summary Book Review ACCGE 2015 Abstracts eBook :

Download or read book ACCGE 2015 Abstracts eBook written by American Association for Crystal Growth (AACG) and published by Coe Truman International, LLC. This book was released on 2015-07-15 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

A compact mode-locked diode laser system for high precision frequency comparison experiments (Band 64)

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Publisher : Cuvillier Verlag
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ISBN 10 : 9783736963993
Pages : 206 pages
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Summary Book Review A compact mode-locked diode laser system for high precision frequency comparison experiments (Band 64) :

Download or read book A compact mode-locked diode laser system for high precision frequency comparison experiments (Band 64) written by Heike Christopher and published by Cuvillier Verlag. This book was released on 2021-04-09 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical frequency combs (OFC) have revolutionized various applications in applied and fundamental sciences that rely on the determination of absolute optical frequencies and frequency differences. The latter requires only stabilization of the spectral distance between the individual comb lines of the OFC, allowing to tailor and reduce system complexity of the OFC generator (OFCG). One such application is the quantum test of the universality of free fall within the QUANTUS experimental series. Within the test, the rate of free fall of two atomic species, Rb and K, in micro-gravity will be compared. The aim of this thesis was the development of a highly compact, robust, and space-suitable diode laser-based OFCG with a mode-locked optical spectrum in the wavelength range around 780 nm. A diode laser-based OFCG was developed, which exceeds the requirements with a spectral bandwidth > 16 nm at 20 dBc, a comb line optical power > 650 nW (at 20 dBc), a pulse repetition rate of 3.4 GHz, and an RF linewidth of the free-running pulse repetition rate < 10 kHz. To realize a proof-of-concept demonstrator module, the diode laser-based OFCG was hybrid-integrated into a space-suitable technology platform that has been developed for future QUANTUS experiments. Proof of sufficient RF stability of the OFCG was provided by stabilizing the pulse repetition rate to an external RF reference. This resulted in a stabilized pulse repetition rate with an RF linewidth smaller than 1.4 Hz (resolution limited), thus exceeding the requirement. The developed diode laser-based OFCG represents an important step towards an improved comparison of the rate of free fall of Rb and K quantum gases within the QUANTUS experiments in micro-gravity.

15th European Workshop on Metalorganic Vapour Phase Epitaxy (EWMOVPE XV) June 2-5, 2013, Aachen, Germany

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Publisher : Forschungszentrum Jülich
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ISBN 10 : 9783893368709
Pages : 390 pages
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Summary Book Review 15th European Workshop on Metalorganic Vapour Phase Epitaxy (EWMOVPE XV) June 2-5, 2013, Aachen, Germany :

Download or read book 15th European Workshop on Metalorganic Vapour Phase Epitaxy (EWMOVPE XV) June 2-5, 2013, Aachen, Germany written by kein Autor and published by Forschungszentrum Jülich. This book was released on 2013 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Solid State Lasers

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Publisher : Springer Science & Business Media
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ISBN 10 : 9781461529989
Pages : 350 pages
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Summary Book Review Solid State Lasers :

Download or read book Solid State Lasers written by Massimo Inguscio and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the lectures and seminars presented at the NATO Ad vanced Study Institute on "Solid State Lasers: New Developments and Appli cations" the fifteenth course of the Europhysics School of Quantum Electronics, held under the supervision of the Quantum Electronics Division of the European Physical Society. The Institute was held at Elba International Physics Center, Marciana Marina, Elba Island, Tuscany, Italy, August 31 -September 11, 1992. The Europhysics School of Quantum Electronics was started in 1970 with the aim of providing instruction for young researchers and advanced students al ready engaged in the area of quantum electronics or wishing to switch to this area from a different background. Presently the school is under the direction of Professors F.T. Arecchi and M. Inguscio, University of Florence, and Prof. H. Walther, University of Munich, and has its headquarters at the National Insti tute of Optics (INO), Florence, Italy. Each time the directors choose a subject of particular interest, alternating fundamental topics with technological ones, and ask colleagues specifically competent in a given area to take the scientific responsibility for that course.

Design and Realization of Novel GaAs Based Laser Concepts

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Publisher : Springer Science & Business Media
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ISBN 10 : 9783642340796
Pages : 150 pages
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Summary Book Review Design and Realization of Novel GaAs Based Laser Concepts :

Download or read book Design and Realization of Novel GaAs Based Laser Concepts written by Tim David Germann and published by Springer Science & Business Media. This book was released on 2013-02-26 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Investigation of slow-axis beam quality degradation in high-power broad area diode lasers

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Publisher : Cuvillier Verlag
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Language : EN, FR, GB
ISBN 10 : 9783736987333
Pages : 158 pages
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Summary Book Review Investigation of slow-axis beam quality degradation in high-power broad area diode lasers :

Download or read book Investigation of slow-axis beam quality degradation in high-power broad area diode lasers written by Martin Winterfeldt and published by Cuvillier Verlag. This book was released on 2018-03-06 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern high-power broad area (BA) diode lasers are important building blocks for the materials processing industry, combining high optical output power with high conversion efficiency. However, their use in direct diode systems, e.g. for sheet metal cutting, is limited due to a poor lateral (slow-axis) beam quality, which is inversely proportional to the beam parameter product (BPP). The main objective of this work was therefore on root cause analy-sis of the factors influencing the diode lasers’ increase in lateral BPP. Hence, a series of diagnostic experiments was conducted, each aiming at a specific potential influence in order to assess its importance. The list of considered effects includes thermal lens shape, epitaxial layer design, lateral carrier profile, process-induced index guiding via dry etched trenches, filamentation, and mechanical strain. Analysis revealed that epitaxial layer structure and chip geometry have considerable impact on thermal lens bowing, which directly correlates with the rate of BPP increase with rising junction temperature. In addition, the suppression of lateral carrier accumulation with deep proton implantation at the BA emitter edges led to a 33% decrease of that deterioration rate. The application of index guiding trenches yielded stabilized near-field dimensions as function of current, but also increased the BPP considerably. Filamentation and mechanical strain were found to have only marginal influence. In addition, this work assesses techniques that aim at reducing the BPP via a reduction of the number of active lateral modes. As a result of a near-field-width selective loss mechanism, diode lasers with an excellent linear radiance of 4.4 W/mm•mrad were fabricated.

Scientific and Technical Aerospace Reports

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ISBN 10 : UIUC:30112050127296
Pages : pages
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Summary Book Review Scientific and Technical Aerospace Reports :

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Proceedings

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ISBN 10 : PSU:000054636095
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Summary Book Review Proceedings :

Download or read book Proceedings written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Electrical & Electronics Abstracts

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ISBN 10 : OSU:32435059588608
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Summary Book Review Electrical & Electronics Abstracts :

Download or read book Electrical & Electronics Abstracts written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Chemical Abstracts

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ISBN 10 : UOM:39015057317482
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Summary Book Review Chemical Abstracts :

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

International Aerospace Abstracts

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ISBN 10 : UOM:39015040314299
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Summary Book Review International Aerospace Abstracts :

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Integrated Optics and Optical Switching

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Publisher : Information Gatekeepers Inc
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ISBN 10 : 1568510624
Pages : 465 pages
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Summary Book Review Integrated Optics and Optical Switching :

Download or read book Integrated Optics and Optical Switching written by IGIC, Inc. Staff and published by Information Gatekeepers Inc. This book was released on 1994 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt:

NASA Information Sciences and Human Factors Program Annual Report, 1987

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ISBN 10 : UIUC:30112106721563
Pages : 223 pages
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Summary Book Review NASA Information Sciences and Human Factors Program Annual Report, 1987 :

Download or read book NASA Information Sciences and Human Factors Program Annual Report, 1987 written by United States. National Aeronautics and Space Administration. Information Sciences and Human Factors Division and published by . This book was released on 1988 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: