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arXiv 2017年

作者： Jain, Vishal Heurlin, Magnus Barrigon, Enrique Bosco, Lorenzo Nowzari, Ali Shroff, Shishir Boix, Virginia Karimi, Mohammad Jam, Reza J. Berg, Alexander Samuelson, Lars Borgström, Magnus T. Capasso, Federico Pettersson, Håkan Solid State Physics and NanoLund Lund University Box 118 LundSE-221 00 Sweden Laboratory of Mathematics Physics and Electrical Engineering Halmstad University Box 823 HalmstadSE-301 18 Sweden School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States

Avalanche photodetectors (APDs) are key components in optical communication systems due to their increased photocurrent gain and short response time as compared to conventional photodetectors. A detector design where the multiplication region is implemented in a large bandgap material is desired to avoid detrimental Zener tunneling leakage currents, a concern otherwise in smaller bandgap materials required for absorption at 1.3/1.55 µm. Self-assembled iii-V semiconductor nanowires offer key advantages such as enhanced absorption due to optical resonance effects, strain-relaxed heterostructures and compatibility with main-stream silicon technology. Here, we present electrical and optical characteristics of single InP and InP/InAsP nanowire APD structures. Temperature-dependent breakdown characteristics of p+-n-n+ InP nanowire devices were investigated first. A clear trap-induced shift in breakdown voltage was inferred from I-V measurements. An improved contact formation to the p+-InP segment was observed upon annealing, and its effect on breakdown characteristics was investigated. The bandgap in the absorption region was subsequently varied from pure InP to InAsP to realize spatially separate absorption and multiplication APDs in heterostructure nanowires. In contrast to the homojunction APDs, no trap-induced shifts were observed for the heterostructure APDs. A gain of 12 was demonstrated for selective optical excitation of the InAsP segment. Additional electron beam-induced current measurements were carried out to investigate the effect of local excitation along the nanowire on the I-V characteristics. Our results provide important insight for optimization of avalanche photodetector devices based on iii-V nanowires. Copyright © 2017, The Authors. All rights reserved.

关键词： Nanowires

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Proceedings of SPIE - The International Society for optical engineering

Proceedings of SPIE - The International Society for Optical ...

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current developments in Lens design and optical engineering XVII

ISBN: (纸本)9781510602861

The proceedings contain 35 papers. The topics discussed include: some methods for determining the limit of potential image quality of optical systems of various complexities using the database;optical design of an ultrashort throw ratio projector with two freeform mirrors;reduce volume of head-up display by image stitching;optical performance of a PDMS tunable lens with automatically controlled applied stress;fabrication of focus-tunable liquid crystal microlens array with spherical electrode;characterization of a tunable liquid-filled lens with minimum spherical aberration;design of a radiance meter with predicted size of source and distance effects;formation of the color image based on the vidicon TV camera;AND efficient 3M PBS enhancing miniature projection optics.

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design investigation of a cost-effective dual-band (MWIR/LWIR) and a wide band optically athermalized application 17

Design investigation of a cost-effective dual-band (MWIR/LWI...

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Conference on current developments in Lens design and optical engineering XVII

作者： Ding, Fujian Washer, Joe Morgen, Daniel ISP OPT 50 S Buckhout St Irvington NY 10533 USA

ISBN: (数字)9781510602861

ISBN: (纸本)9781510602854;9781510602861

Dual-band and wide-band lenses covering both the MWIR and LWIR spectral bands are increasingly needed as dual-band MWIR/LWIR detectors have become prevalent and broadband applications have expanded. currently in dual-band /wide-band applications, the use of more than three elements per lens group and the use of chalcogenide glass is common. This results in expensive systems. Also, many chalcogenides are available only in small diameters, which is a problem for large aperture broadband lenses. In this paper an investigation of cost-effective designs for dual-band MWIR/LWIR lens using only widely available IR materials, specifically Ge, ZnSe and ZnS were performed. An athermalized dual-band MWIR/LWIR using these three materials is presented. The performance analysis of this lens shows that this design form with these three common IR materials works well in certain applications. The required large size blanks of these materials can be easily obtained. Traditional chromatic aberration correction without diffraction for either wide-band or dual-band application was employed. In addition, the methods of harmonic diffraction for dual-band applications, especially with one narrow band, were used for two different presented designs.

关键词： IR Imaging IR Wide-band Lens Dual-band Lens Athermalization Chromatic Aberration Correction Harmonic diffraction

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design of thin InGaAsN(Sb) n-i-p junctions for use in four-junction concentrating photovoltaic devices

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JOURNAL OF PHOTONICS FOR ENERGY 2017年第2期7卷 022502-022502页

作者： Wilkins, Matthew M. Gupta, James Jaouad, Abdelatif Bouzazi, Boussairi Fafard, Simon Boucherif, Abderraouf Valdivia, Christopher E. Ares, Richard Aimez, Vincent Schriemer, Henry P. Hinzer, Karin Univ Ottawa Sch Elect Engn & Comp Sci 25 Templeton St Ottawa ON K1N 6N5 Canada Natl Res Council Canada Inst Microstruct Sci 1200 Montreal RdBldg M-50 Ottawa ON K1A 0R6 Canada CNRS UMI 3463 Lab Nanotechnol Nanosyst LN2 3000 Blvd Univ Sherbrooke PQ J1K 0A5 Canada Univ Sherbrooke Inst Interdisciplinaire Innovat Technol 3IT 3000 Blvd Univ Sherbrooke PQ J1K 0A5 Canada

Four-junction solar cells for space and terrestrial applications require a junction with a band gap of similar to 1 eV for optimal performance. InGaAsN or InGaAsN(Sb) dilute nitride junctions have been demonstrated for this purpose, but in achieving the 14 mA/cm(2) short-circuit current needed to match typical GaInP and GaAs junctions, the open-circuit voltage (V-OC) and fill factor of these junctions are compromised. In multijunction devices incorporating materials with short diffusion lengths, we study the use of thin junctions to minimize sensitivity to varying material quality and ensure adequate transmission into lower junctions. An n-i-p device with 0.65-mu m absorber thickness has sufficient short-circuit current, however, it relies less heavily on field-aided collection than a device with a 1-mu m absorber. Our standard cell fabrication process, which includes a rapid thermal anneal of the contacts, yields a significant improvement in diffusion length and device performance. By optimizing a four-junction cell around a smaller 1-sun short-circuit current of 12.5 mA/cm(2), we produced an InGaAsN(Sb) junction with open-circuit voltage of 0.44 V at 1000 suns (1 sun = 100 mW/cm(2)), diode ideality factor of 1.4, and sufficient light transmission to allow > 12.5 mA/cm(2) in all four subcells. (C) 2017 Society of Photo-optical Instrumentation Engineers (SPIE)

关键词： iii-V multijunction solar cells iii-V multijunction solar cell design dilute nitride InGaAsN four-junction

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optical design and initial Results from NIST's AMMT/TEMPS Facility 3

Optical design and initial Results from NIST's AMMT/TEMPS Fa...

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Conference on Laser 3D Manufacturing iii

作者： Grantham, Steven Lane, Brandon Neira, Jorge Mekhontsev, Sergey Vlasea, Mihaela Hanssen, Leonard NIST 100 Bur Dr Gaithersburg MD 20899 USA Univ Waterloo 200 Univ Ave West Waterloo ON N2L 3G1 Canada

ISBN: (纸本)9781628419733

NIST's Physical Measurement and engineering Laboratories are jointly developing the Additive Manufacturing Measurement Testbed (AMMT)/Temperature and Emittance of Melts, Powders and Solids (TEMPS) facilities. These facilities will be co-located on an open architecture laser-based powder bed fusion system allowing users full access to the system's operation parameters. This will provide users with access to machine-independent monitoring and control of the powder bed fusion process. In this paper there will be emphasis on the AMMT, which incorporates in-line visible light collection optics for monitoring and feedback control of the powder bed fusion process. We shall present an overview of the AMMT/TEMPs program and it goals. The optical and mechanical design of the open architecture powder-bed fusion system and the AMMT will be also be described. In addition, preliminary measurement results from the system along with the current system status of the system the will be described.

关键词： Powder bed fusion Additive manufacturing selective laser melting 3D printing Radiometry

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Low power and high speed CMOS current comparators

Low power and high speed CMOS current comparators

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2016 International Conference on Advances in Electrical, Electronic and Systems engineering, ICAEES 2016

作者： Restu, Wan Irma Idayu Nasir, Binti Wan Mohd Reaz, Md. Mamun Bin Ibne Dept. of Electrical Electronics and System Engineering Universiti Kebangsaan Malaysia Bangi Selangor Malaysia

ISBN: (纸本)9781509028894

Over the past few decades, a current comparator in CMOS technology has been used in the wide range of application in analogue, multiple-valued logic (MVL) circuits and other electronic products. current comparator usually used in analog to digital (ADC) conversion and any sensing detector or devices. The design of comparator has been successfully performed by applying several techniques and approach to improve the performance. This paper presents an overview of evolutionary CMOS current comparator, describing the contributions in low power and high speed according a collection of existing proposal. Various schemes and information have been taken to help researcher who will continue work on significant further developments. Lastly, some consideration of recent architectures such as power consumption and speed in current comparator are presented. © 2016 IEEE.

关键词： Comparators (optical)

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design OF A RECIRCULATING WATER TUNNEL FOR THE STUDY OF HIGH-REYNOLDS NUMBER TURBULENT BOUNDARY LAYERS

DESIGN OF A RECIRCULATING WATER TUNNEL FOR THE STUDY OF HIGH...

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ASME International Mechanical engineering Congress and Exposition (IMECE2015)

作者： Daniel, Libin Mohagheghian, Shahrouz Dunlap, Dalton Ruhmann, Eric Elbing, Brian R. Gulfstream Aerosp Corp Savannah GA USA Oklahoma State Univ Stillwater OK USA

ISBN: (纸本)9780791857472

This paper reports on the design and fabrication of a high Reynolds number recirculating water tunnel, which will be used primarily for the study of turbulent boundary layers with an emphasis on drag reduction applications. The primary design specifications were (i) achieve a momentum thickness based Reynolds number above 10,000, (ii) maximize optical access, and (iii) minimize flow non-uniformity. This paper discusses the design considerations and procedures to meet each of these design criteria as well as the manufacturing of the components, installation, and design of auxiliary systems such as the pressure regulation system. There are several recirculating water tunnels at universities that can achieve comparable Reynolds numbers, but they were either built with at least double the budget of the current project or are refurbished tunnels from other laboratories (i.e. key design considerations were already fixed). Thus, the current work offers a guide for the overall design of a low-cost, high-Reynolds number water tunnel. A brief review of other recirculating high-Reynolds number water tunnels is included. currently, installation has begun with the fabrication complete.

关键词： water tunnel facility high-Reynolds number fluid mechanics drag reduction

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Low-stress mounting configuration design for large aperture laser transport mirror

Low-stress mounting configuration design for large aperture ...

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International Symposium on Advanced optical design and Manufacturing Technologies / International Symposium on Astronomical Telescope and Instrumentation

作者： Zhang, Zheng Quan, Xusong Yao, Chao Wang, Hui Tsinghua Univ Dept Mech Engn Beijing 100084 Peoples R China China Acad Engn Phys Res Ctr Laser Fus Mianyang 621900 Sichuan Peoples R China

ISBN: (数字)9781510607675

ISBN: (纸本)9781510607675

TM1-6S1 large aperture laser transport mirror is a crucial optical unit of high power solid-state laser in the Inertial Confinement Fusion (ICF) facility. This article focuses on the low-stress and precise mounting method of large-aperture mirror. Based on the engineering practice of SG-iii, the state-of-the-art and key problems of current mounting configuration are clarified firstly. Subsequently, a brand new low-stress mounting configuration with flexure supports is proposed. Opto-mechanical model of the mirror under mounting force is built up with elastic mechanics theory. Further, numerical methods and field tests are employed to verify the favorable load uniform capacity and load adjust capacity of flexure supports. With FEM, the relation between the mounting force from new configuration and the mirror surface distortion (wavefront error) is clarified. The novel mounting method of large aperture optics could be not only used on this laser transport mirror, but also on the other transmission optics and large crystals in ICF facilities.

关键词： lasers high power laser large aperture mirror low-stress mounting wavefront error

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Additive manufacturing of glass for optical applications 3

Additive manufacturing of glass for optical applications

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Conference on Laser 3D Manufacturing iii

作者： Luo, Junjie Gilbert, Luke J. Bristow, Douglas A. Landers, Robert G. Goldstein, Jonathan T. Urbas, Augustine M. Kinzel, Edward C. Missouri Univ Sci & Technol Mech & Aerosp Engn 400 W 13th St Rolla MO 65401 USA Air Force Res Lab Mat & Mfg Directorate Wright Patterson AFB OH 45433 USA

ISBN: (纸本)9781628419733

Glasses including fused quartz have significant scientific and engineering applications including optics, communications, electronics, and hermetic seals. This paper investigates a filament fed process for Additive Manufacturing (AM) of fused quartz. Additive manufacturing has several potential benefits including increased design freedom, faster prototyping, and lower processing costs for small production volumes. However, current research in AM of glasses is limited and has focused on non-optical applications. Fused quartz is studied here because of its desirability for high-quality optics due to its high transmissivity and thermal stability. Fused quartz also has a higher working temperature than soda lime glass which poses a challenge for AM. In this work, fused quartz filaments are fed into a CO2 laser generated melt pool, smoothly depositing material onto the workpiece. Single tracks are printed to explore the effects that different process parameters have on the morphology of printed fused quartz. A spectrometer is used to measure the thermal radiation incandescently emitted from the melt pool. Thin-walls are printed to study the effects of layer-to-layer height. Finally, a 3D fused quartz cube is printed using the newly acquired layer height and polished on each surface. The transmittance and index homogeneity of the polished cube are both measured. These results show that the filament fed process has the potential to print fused quartz with optical transparency and of index of refraction uniformity approaching bulk processed glass.

关键词： Fused quartz additive manufacturing optically transparent

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Millimeter-wave receivers for wireless communications. 1

Millimeter-wave receivers for wireless communications. 1

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作者： Overmiller, Brock Morgan. University of Delaware.bElectrical and Computer Engineering.

学位级别：M.S.

The modern communications environment is becoming an increasingly crowded place, resulting in rapidly increasing demands on current technology. Military and civilian operations require the ability to locate and decode all communication signals in the environment. However, developments in RADAR RAdio Detection And Ranging) and communications technology are making it harder to effectively identify and maintain bandwidth usage for everyone. Millimeter waves---waves measured between one millimeter to one centimeter in wavelength---have only recently been explored as a new technology to replace the augment receiver architectures. These small wavelengths introduce many engineering challenges, such as: large atmospheric losses, poor sensitivity, and expensive electronic equipment. With growing developments in Microwave Photonics, low-noise RF amplifiers and high-speed modulators have demonstrated the ability to design RF communication links in the millimeter wave regime to counter such problems. However, despite these developments, toward a cost-effective, spatial division multiplexing SDM) receiver concept has not proved capable of being implemented as part of the next generation 5G wireless network infrastructure. To this end, we present a novel receiver architecture utilizing an optically addressed phased-array millimeter wave receiver based on optical-upconversion and signal recovery. This receiver is capable of geolocation and spatial multiplexing of multiple Tunable optically Paired Source TOPS) communication signals in its scene. Operating at 35 GHz, the receiver up-converts the received RF onto an optical sideband, which, to our advantage, contains all of the frequency, amplitude, and phase information of the received signals. Subsequent optical processing allows routing of the sideband to a free space detector port. Photomixing a coherent optical local oscillator LO) with the optical sideband performs heterodyne down-conversion to an Intermediate Frequency IF) whe

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