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Conference on vertical External Cavity Surface Emitting Lasers (vECSELs) vIII

作者： Sverre, T. Chen Woods, J. R. C. Shaw, E. A. Hua, Ping Apostoulopoulos, v. Wilkinson, J. S. Tropper, A. C. Univ Southampton Dept Phys & Astron Highfield Rd Southampton SO17 1BJ Hants England Univ Southampton Optoelect Res Ctr Highfield Rd Southampton Southampton SO17 1BJ Hants England

ISBN: (数字)9781510615168

ISBN: (纸本)9781510615168;9781510615151

Tantalum pentoxide (Ta2O5) is a promising material for mass-producible, multi-functional, integrated photonics circuits on silicon, exhibiting robust electrical, mechanical and thermal properties, as well as good CMOS compatibility. In addition, Ta2O5 has been reported to demonstrate a non-linear response comparable to that of chalcogenide glass, in the region of 3-6 times larger than that of materials such as silica (SiO2) or silicon nitride (Si3N4). In contrast to Si-based dielectrics, it will accept trivalent ytterbium and erbium dopant ions, opening the possibility of on-chip amplification. The high refractive index of Ta2O5 is consistent with small guided mode cross-section area, and allows the construction of micro-ring resonators. Propagation losses as low as 0.2 dB/cm have been reported. In this paper we describe the design of a planar Ta2O5 waveguides optimised for the generation of coherent continuum with near infrared pulse trains at kW peak powers. The Pulse Repetition Frequency (PRF) of the vECSEL can be tuned to a sub-harmonic of the planar micro-ring and the optical pump power applied to the vECSEL can be adjusted so that mode-matching of the vECSEL pulse train with the micro-ring resonator can be achieved. We shall describe the fabrication of Ta2O5 guiding structures, and the characterisation of their nonlinear and other optical properties. Characterisation with conventional lasers will be used to assess the degree of coherent spectral broadening likely to be achievable using these devices when driven by mode-locked vECSELs operating near the current state-of- art for pulse energy and duration.

关键词： vECSEL Mode-locked Frequency Combs Supercontinuum

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design of photovoltaics for modules with 50% efficiency

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ENERGY SCIENCE & engineering 2017年第2期5卷 69-80页

作者： Warmann, Emily C. Flowers, Cristofer Lloyd, John Eisler, Carissa N. Escarra, Matthew D. Atwater, Harry A. CALTECH 1200 E Calif Blvd Pasadena CA 91125 USA E O Lawrence Berkeley Natl Lab Berkeley CA USA Tulane Univ New Orleans LA 70118 USA

We describe a spectrum splitting solar module design approach using ensembles of 2-20 subcells with bandgaps optimized for the AM1.5D spectrum. Device physics calculations and experimental data determine radiative efficiency parameters for III-v compound semiconductor subcells and enable modification of conventional detailed balance calculations to predict module efficiency while retaining computational speed for a wide search of the design space. Accounting for nonideal absorption and recombination rates due to realistic material imperfections allows us to identify the minimum subcell quantity, quality, electrical connection configuration, and concentration required for 50% module efficiency with realistic optical losses and modeled contact resistance losses. We predict a module efficiency of 50% or greater will be possible with 7-10 electrically independent subcells in a spectral splitting optic at 300-500 suns concentration, assuming a 90% optical efficiency and 98% electrical efficiency, provided the subcells can achieve an average external radiative efficiency of 3-5% and a short circuit current that is at least 90% of the ideal. In examining spectrum splitting solar cells with both series-connected and electrically independent subcells, we identify a new design trade-off independent of the challenges of fabricating optimal bandgap combinations. Series-connected ensembles, having a single set of electrical contacts, are less sensitive to lumped series resistance losses than ensembles where each subcells are contacted independently. By contrast, ensembles with electrically independent subcells can achieve lower radiative losses when the subcells are designed for good optical confinement. Distributing electrically independent subcells in a concentrating receiver module allows flexibility in subcell selection and fabrication, and can achieve ultra-high efficiency with conventional III-v cell technology.

关键词： Efficiency photovoltaic design photovoltaic modules spectrum splitting

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Laser diode drive method with narrow-width and high-peak current for multi-line LIDAR

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Journal of Measurement Science and Instrumentation 2019年第3期10卷 246-253页

作者： LI Xu DUAN Fa-jie MA Ling WANG Xian-quan JIANG Jia-jia FU Xiao State Key Laboratory of Precision Measuring Technology and Instruments Tianjin University Tianjin 300072 China

Light detection and ranging (LIDAR) based on time of flight (TOF) method is widely used in many fields related to distance measurement. LIDAR generally uses laser diode (LD) to emit the pulsed laser with high peak power and short duration to ensure a large distance measurement range and eye safety. To achieve this goal, we propose a pulsed LD drive method producing the drive current with high peak and narrow pulse width. We analyze the key issues and related theories of the drive current generation based on this method and design an LD driver. A model of drive current generation is established and the influence of operating frequency on drive current is discussed. The LD driver is simulated by software and verified by experiments. The working frequency of the driver changes from 20 kHz to 100 kHz and the charging voltage is set at 130 v. The current produced by this driver has a duration of 8.8 ns and a peak of about 35 A, and the peak output optical power of the LD exceeds 75 W.

关键词： light detection and ranging(LIDAR) distance measurement laser diode (LD) driver pulsed current

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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 XvIII 2017

ISBN: (纸本)9781510612075

The proceedings contain 35 papers. The topics discussed include: wavefront analysis from its slope data;parametric diffraction efficiency of non-paraxial sinusoidal reflection gratings;camera system MTF: combining optic with detector;diffraction and geometrical optical transfer functions: calculation time comparison;linear decomposition of the optical transfer function for annular pupils;assembly of a micro-optical resonator based on silicon micro mirrors for use in gyroscopes;and fabrication of multi-focal microlens array on curved surface for wideangle camera module.

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Synthesis of a Sheet Beam Electron optical System with a Field Emission Cathode

Synthesis of a Sheet Beam Electron Optical System with a Fie...

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UK, Europe, China Millimeter Waves and THz Technology Workshop (UCMMT)

作者： Aleksei v. Danilushkin Anton A. Burtsev Igor A. Navrotsky Kirill v. Shumikhin Nikita M. Ryskin Yuri Gagarin State Technical University of Saratov Saratov Russia Saratov Branch A. Kotel'nikov Institute of Radio Engineering and Electronics RAS Saratov Russia

ISBN: (数字)9781538674970

ISBN: (纸本)9781538674987

The results of design and simulation of an electron-optical system with compression sheet electron beam and field emission cathode are presented. The result of modeling the electron gun at linear compression ~ 10, the beam of current 0.1A has the size of 0.125·0.7 mm 2 are performed. The electric field at the cathode is 0.4·10 5 v/cm at anode voltage 20000 v. The feasibility of obtaining a high density sheet beam focusing of electron gun consisting of field emission cathode is discussed.

关键词： Cathodes Electron beams Magnetic fields Electron guns Electric fields Electric potential Mathematical model

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Multi-band filter design with less total film thickness for short-wave infrared 18

Multi-band filter design with less total film thickness for ...

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Conference on current developments in Lens design and optical engineering XvIII

作者： Yan, Yung-Jhe Chien, I-Pen Chen, Po-Han Chen, Sheng-Hui Tsai, Yi-Chun Ou-Yang, Mang Natl Chiao Tung Univ Dept Elect & Comp Engn Hsinchu Taiwan Natl Cent Univ Dept Opt & Photon Taoyuan Taiwan

ISBN: (纸本)9781510612082;9781510612075

A multi-band pass filter array was proposed and designed for short wave infrared applications. The central wavelength of the multi-band pass filters are located about 905 nm, 950 nm, 1055 nm and 1550 nm. In the simulation of an optical interference band pass filter, high spectrum performance (high transmittance ratio between the pass band and stop band) relies on (1) the index gap between the selected high/low-index film materials, with a larger gap correlated to higher performance, and (2) sufficient repeated periods of high/low-index thin-film layers. When determining high and low refractive index materials, spectrum performance was improved by increasing repeated periods. Consequently, the total film thickness increases rapidly. In some cases, a thick total film thickness is difficult to process in practice, especially when incorporating photolithography liftoff. Actually the maximal thickness of the photoresist being able to liftoff will bound the total film thickness of the band pass filter. For the application of the short wave infrared with the wavelength range from 900nm to 1700nm, silicone was chosen as a high refractive index material. Different from other dielectric materials used in the visible range, silicone has a higher absorptance in the visible range opposite to higher transmission in the short wave infrared. In other words, designing band pass filters based on silicone as a high refractive index material film could not obtain a better spectrum performance than conventional high index materials like TiO2 or Ta2O5, but also its material cost would reduce about half compared to the total film thickness with the conventional material TiO2. Through the simulation and several experimental trials, the total film thickness below 4 um was practicable and reasonable. The fabrication of the filters was employed a dual electric gun deposition system with ion assisted deposition after the lithography process. Repeating four times of lithography and deposition p

关键词： optical interference filter Photolithography Bandpass filter Short-wave infrared

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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

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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Tactical versus space cryocoolers: A comparision 2

Tactical versus space cryocoolers: A comparision

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Tri-Technology Device Refrigeration (TTDR) II 2017

作者： Arts, R. Mullié, J. Leenders, H. De Jonge, G. Benschop, T. Thales Cryogenics B.V. Netherlands

ISBN: (数字)9781510608627

ISBN: (纸本)9781510608610

In recent years, several space cryocooler developments have been performed in parallel at Thales Cryogenics. On one end of the spectrum are research programmes such as the ESA-funded 30-50 K system developed in cooperation with CEA and Absolut System and the LPT6510 cooler developed in cooperation with Absolut System. On the other end of the spectrum are commercial designs adapted for space applications, such as the LPT9310 commercial coolers delivered for JPL's ECOSTRESS instrument and the LSF9199/30 SADA-compatible cooler delivered for various space programmes at Sofradir. In this paper, an overview is presented of the latest developments regarding these coolers. Initial performance results of the 30-50K cooler are discussed, pending developments for the LPT6510 cooler are presented, and the synergies between COTS and space are reviewed, such as design principles from space coolers being applied to an upgraded variant of the COTS LPT9310, as well as design principles from COTS coolers being applied to the LPT6510 for improved manufacturability. © 2017 SPIE.

关键词： Space applications

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Synthesis, Assembly, and Applications of Hybrid Nanostructures for Biosensing

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CHEMICAL REvIEWS 2017年第20期117卷 12942-13038页

作者： Zhang, Shuaidi Geryak, Ren Geldmeier, Jeffrey Kim, Sunghan Tsukruk, vladimir v. Georgia Inst Technol Sch Mat Sci & Engn Atlanta GA 30332 USA

The robust, sensitive, and selective detection of targeted biomolecules in their native environment by prospective nanostructures holds much promise for real-time, accurate, and high, throughput biosensing. However, in Order to be competitive, current biosensor nanotechnologies need significant improvements, especially in specificity, integration, throughput rate, and long-term stability in complex bioenvironments. Advancing biosensing nanotechnologies in chemically "noisy" bioenvironments require careful engineering of nanoscale components that are highly sensitive, biorecognition ligands that are capable of exquisite selective, binding, and seamless integration at a level current devices have yet to achieve. This review summarizes recent advances in the synthesis, assembly, and applications of nanoengineered reporting and transducing components critical for efficient biosensing. First, major classes of nanostructured components, both inorganic reporters and organic transducers, are discussed in the context of the synthetic control of their individual compositions, shapes, and properties. Second, the design of surface functionalities and transducing path, the characterization of interfacial architectures, and the integration of multiple nanoscale components into multifunctional ordered nanostructures are extensively examined. Third, examples of current biosensing structures created from hybrid nanomaterials are reviewed, with a distinct, emphasis on the need to tailor nanosensor designs to specific operating environments. Finally, we offer a perspective on the future developments of nanohybrid materials and future nanosensors, outline possible directions to be pursued that may yield breakthrough results, and envision the exciting potential of high-performance nanomaterials that will cause disruptive improvements in the field of biosensing.

关键词： Nanostructures Sensors Peptides and proteins Biotechnology Biopolymers

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Effect of Continuous and Pulsed current Gas Tungsten Arc Welding on Dissimilar Weldments Between Hastelloy C-276/AISI 321 Austenitic Stainless Steel

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JOURNAL OF MATERIALS engineering AND PERFORMANCE 2017年第3期26卷 1146-1157页

作者： Sharma, Sumitra Taiwade, Ravindra v. vashishtha, Himanshu VNIT Dept Met & Mat Engn Nagpur 440010 Maharashtra India

In the present investigation, an attempt has been made to join Hastelloy C-276 nickel-based superalloy and AISI 321 austenitic stainless steel using ERNiCrMo-4 filler. The joints were fabricated by continuous and pulsed current gas tungsten arc welding processes. Experimental studies to ascertain the structure-property co-relationship with or without pulsed current mode were carried out using an optical microscope and scanning electron microscope. Further, the energy-dispersive spectroscope was used to evaluate the extent of microsegregation. The microstructure of fusion zone was obtained as finer cellular dendritic structure for pulsed current mode, whereas columnar structure was formed with small amount of cellular structure for continuous current mode. The scanning electron microscope examination witnessed the existence of migrated grain boundaries at the weld interfaces. Moreover, the presence of secondary phases such as P and mu was observed in continuous current weld joints, whereas they were absent in pulsed current weld joints, which needs to be further characterized. Moreover, pulsed current joints resulted in narrower weld bead, refined morphology, reduced elemental segregation and improved strength of the welded joints. The outcomes of the present investigation would help in obtaining good quality dissimilar joints for industrial applications and AISI 321 ASS being cheaper consequently led to cost-effective design also.

关键词： AISI 321 austenitic stainless steel continuous current gas tungsten arc welding fusion zone Hastelloy C-276 migrated grain boundaries pulse current gas tungsten arc welding

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