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Author: L. Wandinger
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Book Description
The essential features in the design, development, and performance of GaAs p-n junction laser diodes with high output in the coherent beam for application in secure communication systems are discussed. After a brief review of device design principles, the technology of wafer preparation, diffusion of extremely planar p-n junctions and the formation of ohmic, low resistance, area contacts developed at this Command is presented. Measurement techniques to determine the performance characteristics of these lasers such as threshold current density, output power, external quantum efficiency, spectral distribution and linewidth of emitted radiation are discussed. Experimental units with a total average power output in the coherent beam of more than three watts corresponding to a quantum efficiency of 15 percent have been made. (Author).
Author: L. Wandinger
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Book Description
The essential features in the design, development, and performance of GaAs p-n junction laser diodes with high output in the coherent beam for application in secure communication systems are discussed. After a brief review of device design principles, the technology of wafer preparation, diffusion of extremely planar p-n junctions and the formation of ohmic, low resistance, area contacts developed at this Command is presented. Measurement techniques to determine the performance characteristics of these lasers such as threshold current density, output power, external quantum efficiency, spectral distribution and linewidth of emitted radiation are discussed. Experimental units with a total average power output in the coherent beam of more than three watts corresponding to a quantum efficiency of 15 percent have been made. (Author).
Author: Roland Diehl
Publisher: Springer Science & Business Media
ISBN: 3540478523
Category : Science
Languages : en
Pages : 420
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Book Description
Starting from the basics of semiconductor lasers with emphasis on the generation of high optical output power the reader is introduced in a tutorial way to all key technologies required to fabricate high-power diode-laser sources. Various applications are exemplified.
Author: Shuji Nakamura
Publisher: Springer Science & Business Media
ISBN: 366203462X
Category : Science
Languages : en
Pages : 348
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Book Description
In 1993, the author, Shuji Nakamura developed the first commercially available blue and green light-emitting diodes. Now he has made the most important breakthrough in solid state laser techniques to date - the first blue semiconductor laser based on GaN. Here, Dr. Nakamura discusses the physical concept and basic manufacturing technology of these new blue light-emitting and laser diodes. he shows how this represents a new era in commercial applications for semiconductors, including displays, road and railway signalling, lighting, scanners, optical data storage, and much more. Moreover, Nakamura provides fascinating background information on the extraordinary realisation of an extremely successful concept of research and development. Of interest to researchers as well as engineers.
Author: Thorben Kaul
Publisher: Cuvillier Verlag
ISBN: 3736963963
Category : Science
Languages : en
Pages : 136
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Book Description
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.
Author: R. Szweda
Publisher: Elsevier
ISBN: 0080530435
Category : Technology & Engineering
Languages : en
Pages : 547
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Book Description
This report examines the development of the diode laser industry over a six-year period, 2000 to 2005, incorporating analysis of trends in markets, technologies and industry structure. It is designed to provide key information to users and manufacturers of substrates, epitaxial wafers (epiwafers) and devices. The coverage includes components, laser diodes, and the semiconducting (SC) wafers and epiwafers on which most of these devices are made. The geographical coverage of the report includes North America, Japan and Europe, which together will account for over 90% of the production and consumption of diode laser materials and devices over the next five years. However, many other countries have activities in this field including South-East Asia (Taiwan, South Korea, Singapore, Malaysia etc), China, India, Australia and Eastern Europe (Russia, Poland, Hungary, the Czech Republic) amongst others. Activities in these countries are commented on in the text where relevant, but are not quantified in the market data. Chapter 1 is an introduction to the market study. Chapter 2 contains an executive summary. Chapter 3 overviews materials markets. The size, quality, and particularly the price, of substrates and wafers are key factors in determining the ability of companies to produce competitive laser products. Chapter 3 also examines trends in materials technologies for laser diodes, the impact of the device markets on wafer demand, and the main suppliers. This chapter introduces the semiconductor materials that are presently or will likely become important to the fabrication of diode laser devices. The principal distinguishing properties of these materials are explained with reference to their application. Chapter 4 chapter examines the basic application sectors for laser diode devices as well as the basic commercial opportunities, changes and forces acting within each sector. The chapter also examines the market for the basic types of device as well as the promising newer types. For each type of device, market data and forecasts are provided and future prospects described. The application data are presented for the following industrial groups: • Automotive • Computers • Consumer • Industrial • Military and Aerospace • Telecommunications • Others A full 5-year forecast and analysis is provided by application and region. Chapter 5 is a technology overview. In this chapter a background and overview of developments in the principal technological R&D and production processes for devices is provided. The main focus is on the most important enabling technology for the production of the present and future generations of laser diodes and related devices. This process is crystal growth and involves the following sequence: • Bulk growth of single crystals • Epitaxial growth of semiconductor single crystal layers • Ion implantation • Device fabrication, ie gate and contact formation, etc • Packaging & test Chapter 6 profiles substrate suppliers, epiwafers suppliers and merchant and captive producers of GaAs devices. Chapter 7 lists universities and selected industrial labs involved in the areas of diode laser research. Chapter 8 is a directory of suppliers. Chapter 9 provides acronyms and exchange rates.
Author: Roland Diehl
Publisher: Springer Science & Business Media
ISBN: 3540666931
Category : Medical
Languages : en
Pages : 420
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Book Description
With Contributions by Numerous Experts
Author: Mohamed Elattar
Publisher: Cuvillier Verlag
ISBN: 3689520479
Category :
Languages : en
Pages : 124
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Book Description
GaAs-based 9xx-nm broad-area diode lasers (BALs) offer the highest optical power (Popt) among diode lasers and the highest conversion efficiency (ηE) among all light sources. Therefore, they are widely used in material processing applications (e.g. metal cutting), which additionally require high beam quality (i.e. low beam parameter product BPP), typically limited in BALs along the lateral axis (BPPlat). Enhancing BAL performance is dependent on identifying the thermal and non-thermal limiting mechanisms, and implementing design changes to minimize their effects. In this work, two novel approaches based on lateral structuring are developed, aiming to overcome different limiting mechanisms acting along the lateral axis. First, the enhanced self-aligned lateral structure (eSAS) is based on integrating structured current-blocking layers outside the BAL stripe to centrally confine current and charge carriers, thereby suppressing lateral current spreading and lateral carrier accumulation. Two eSAS variants are optimized using simulation tools, then realized in multiple wafer processes, followed by characterization of mounted BALs. eSAS BALs exhibit state-of-the-art Popt and lateral brightness (Popt/BPPlat), with clear benefits over standard gain-guided BALs in terms of threshold, BPPlat and peak ηE. The second approach is chip-internal thermal path engineering, based on structured epitaxial layers replaced outside the stripe by heat-blocking materials to centrally confine heat flow. This flattens the lateral temperature profile (i.e. reduces thermal lensing) around the active zone, which is associated with enhanced brightness. Finite-element thermal simulations are used to estimate the benefits of this approach, thereby motivating its practical realization in future studies.
Author: Shuji Nakamura
Publisher: Springer Science & Business Media
ISBN: 3662041561
Category : Science
Languages : en
Pages : 373
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Book Description
From the reviews of the first edition: "The technical chapters will be lapped up by semiconductor specialists keen to know more [...] the book includes fascinating material that answers the question: why did Nakamura succeed where many, much larger, research groups failed." New Scientist
Author: Friedrich Bachmann
Publisher: Springer
ISBN: 0387347291
Category : Science
Languages : en
Pages : 553
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Book Description
This book summarizes a five year research project, as well as subsequent results regarding high power diode laser systems and their application in materials processing. The text explores the entire chain of technology, from the semiconductor technology, through cooling mounting and assembly, beam shaping and system technology, to applications in the processing of such materials as metals and polymers. Includes theoretical models, a range of important parameters and practical tips.
Author: John Evan Johnson
Publisher:
ISBN:
Category :
Languages : en
Pages : 202
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Book Description
