Inherently mode-hop-free distributed Bragg reflector (DBR) laser array

An inherently mode-hop-free tuning of 4.5 nm was achieved with a short-active-region distributed Bragg reflector (DBR) laser. The DBR laser contains no phase-adjustment electrode, which greatly simplifies the tuning. Fast tuning of several nanoseconds and error-free operation for 2.5-Gbit/s direct modulation were also observed. A 4-ch array of short-active-region DBR lasers achieved wavelength tuning of 12.5 nm.     

High-power laser diodes with dry-etched mirror facets andintegrated monitor photodiodes

High-power broad-area InGaAs-AlGaAs-GaAs single-quantum-well separate-confinement heterostructure (SQW-GRINSCH) lasers with dry-etched mirror facets and integrated monitor photodiodes have been investigated. A multilayer resist system has been employed as a mask for the chemically assisted ion-beam etching (CAIBE) process resulting in vertical and smooth laser facets. Thick electroplated gold layers on top of the ohmic contacts improve the heatsinking of the lasers leading to reasonable continuous-wave (CW) output powers even when the devices are mounted junction-side up. Monolithically integrated monitor photodiodes provide a linear response to the optical output powers of the laser diodes. The properties of broad-area lasers with dry-etched and cleaved facets are almost identical, Record values for the CW output powers of 2.59 W per uncoated facet and wall-plug efficiencies of more than 55% have been achieved with junction-side-down mounted devices     

Short cavity erbium/ytterbium fiber lasers mode-locked with asaturable Bragg reflector

We present short cavity erbium/ytterbium fiber lasers that are passively mode-locked with a saturable Bragg reflector. The lasers produce sub-500-fs pulses at fundamental cavity repetition rates as high as 300 MHz. Stable passive harmonic operation increases the repetition rate to 2.0 GHz. The mode-locking mechanism in both the normal and anomalous group velocity dispersion regimes is investigated using complete analytical and numerical models and direct comparison with the experimental results. A simple technique for accurately measuring the total cavity dispersion is presented     

InGaAs angled-grating distributed Bragg reflector lasers integrated with grating outcoupler for collimation

An angled-grating distributed Bragg reflector (DBR) laser integrated with a grating outcoupler (GO) is proposed and demonstrated. It consists of an angled broad-area gain stripe surrounded by angled DBR (/spl alpha/-DBR) gratings parallel to the gain stripe and two DBR gratings for feedback at the stripe ends, and a GO for emitting a collimated output beam. Due to distributed Bragg reflection in the /spl alpha/-DBR gratings, filamentation can be suppressed. Single-mode lasing up to 69 mW peak power was obtained under pulse condition. A collimated output beam with divergence angles, close to the diffraction limit, was obtained. These results confirm the effectiveness of the /spl alpha/-DBR gratings.     

InGaN multiquantum-well-structure laser diodes with GaN-AlGaNmodulation-doped strained-layer superlattices

InGaN multiquantum-well-structure (MQW) laser diodes with Al_0.14Ga_0.86N-GaN modulation doped strained-layer superlattice (MD-SLS) cladding layers grown on an epitaxially laterally overgrown GaN substrate was demonstrated to have a lifetime of more than 2300 h under the condition of room-temperature continuous-wave operation. The self-pulsation was observed with a frequency of 3.5 GHz. The relative intensity noise less than -145 dB/Hz was obtained even at the 6% optical feedback using the high-frequency modulation of 600 MHz. The threshold carrier density of the InGaN MQW-structure laser diodes was estimated to be 3×10¹⁹/cm³ using a carrier lifetime of 1.8 ns     

High-power high-efficiency 660-nm laser diodes for DVD-R/RW

A kink mechanism in 660-nm laser diodes (LDs) has been studied experimentally. The experiments revealed that the main origin of the kink is a refractive index change due to heat generation in the stripe portion, and the kink power can be increased by improving the temperature characteristics of the LD. A newly developed LD, based on this result, shows stable lateral mode operation up to 190 mW at 80/spl deg/C. This is the highest power recorded among narrow stripe LDs with a wavelength of 660 nm. This LD is suitable for the next generation of high-speed (8x-) DVD-R/RW drives necessitating 140 mW class LDs.     

Oxynitride/nitride phosphors for white light-emitting diodes (LEDs)

Oxynitride/nitride phosphors have attracted significant attention recently because they have promising luminescence properties and superior thermal and chemical stabilities which predestinates them for use in white LEDs to generate white light. This paper reports on luminescence spectra of Eu²⁺ or Ce³⁺-activated α-SiAlON, β-SiAlON, and alkaline earth silicon nitride (M₂Si₅N₈, M = Ca, Sr, Ba). A single broad emission band is observed for all samples, and the emission color depends on the type of activators and host lattice: α-SiAlON:Ce³⁺ (blue), α-SiAlON:Eu²⁺ (yellow), β-SiAlON:Eu²⁺ (green), and M₂Si₅N₈:Eu²⁺ (red). The excitation spectrum of these oxynitride/nitride phosphors covers a wide range from ultraviolet to visible light, enabling them to be used for white LEDs when an ultraviolet or blue LED chip is combined.     

All-optical ASK/DPSK label-swapping and buffering using Fabry-Perot laser diodes

We describe an approach for optical label encoding that allows the realization of all-optical label-swapping in optical packet-switched networks. The proposed method is based on a combination of the amplitude-shift-keying (ASK) modulated payload with the differential phase-shift keying (DPSK) modulated label on the same optical carrier. We demonstrate an implementation using dual-wavelength injection locking (DWIL) of a Fabry-Perot laser diode. Bit-error-rate measurements were performed for the 10-Gb/s payload, and the 2.5-Gb/s label showed the feasibility of the proposed method. An all-optical buffer for the two-level ASK/DPSK optically labeled packets is also described. The buffer is implemented by routing the packet via a delay line if potential contention is predicted. Error-free operation was also achieved.     

融合局部熵二维熵的空中目标跟踪算法研究

提出了一种将局部熵算法和二维熵算法结合的空中目标跟踪算法。此算法通过一定的准则合理地融合局部熵和二维熵算法,然后进行目标定位跟踪。既能实现空中小目标的准确跟踪,也能实现空中面目标的准确跟踪;同时针对大小不变的带宽窗口可能导致目标跟踪丢失的问题,采用了自动调节带宽窗口的方法,让跟踪结果稳定可靠。并且算法实现运用了局部熵和二维熵的快速算法,大大减小了系统检测模块所消耗的时间,使跟踪具有实时性和鲁棒性,此外也能将融合算法有效地移植到DSP上,实现工程应用。此算法可以应用于导弹跟踪、空中监控、海空预警等许多领域。     

Numerical drift-diffusion simulation of Auger hot electron transport in Ingaasp/Inp double heterojunction laser diodes

This paper considers the adaptation of drift-diffusion device simulation methodology to study Auger-recombination-induced hot electron transport characteristics in InGaAsP/InP double heterostructure laser diodes. In order to model the transport behaviour of the Auger hot electrons, we decompose the conventional electron current continuity equation into two components, with one for the Auger hot electrons and the other for the low-energy electrons. These equations, which use the energy relaxation time parameter to model the dynamics of the Auger hot electrons, are then coupled with the hole current continuity equation and the Poisson equation to obtain self-consistent solutions. Results from the case studies of one-dimensional N-p-P InGaAsP/InP double heterojunction laser diodes with material composition corresponding to 1·3 μm and 1·55 μm wavelength emissions are presented. We have observed that hot electrons generated through Auger recombination inside the active region can spread into both the N- and the P-InP cladding layers. Within the drift-diffusion framework, it is demonstrated that the hot electron concentration in the N-InP cladding layer can be five orders of magnitude higher than that in the P-InP cladding layer. Because energy transport of the hot electrons in not modelled under the drift-diffusion approximation, the simulated results are discussed to highlight some of the possible limitations in using drift-diffusion physics to study Auger hot electron transport behaviour. The importance of taking energy transport into account is emphasized.     

Improved reverse recovery of self-adaptingp emitter efficiency diodes (SPEED)

Contents A fastpnn ⁺ power diode is described, which due to a self-adaptingp emitter efficiency shows an essentially improved reverse recovery behaviour. Thep emitter consists of ap ⁺ region with high injection efficiency and of ap region which has low injection efficiency and densely intersperses thep ⁺ region. The lateral extension of thep ⁺ areas between thep elements and the vertical doping profile of thep region are chosen in such a manner, that the high efficiency of thep ⁺ region becomes effective only at high currents, reducing the forward voltage drop. Up to the normal operative forward current the carrier concentration at the anode side of the base region is smaller than near thenn ⁺ junction. By commutation, this results in a strong reduction of the peak reverse current and a significantly softer reverse current decay compared with standard diodes designed for the same forward and blocking voltages. Modeling calculations as well as measurements on the operation principle and switching behaviour are presented.

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Verbessertes Rückwärtserholungsverhalten von Dioden mit sich selbst anpassenderp-Emitter Efficiency

Übersicht Es wird eine schnellepnn ⁺-Leistungsdiode beschrieben, deren Rückwärtserholungsverhalten (Recovery-Verhalten) infolge einer sich selbst anpassendenp-Emitter Efficiency stark verbessert ist. Diep-Zone besteht aus einemp ⁺-Bereich mit hohem Emitterwirkungsgrad und einemp-Bereich mit niedrigem Injektionsvermögen der denp ⁺-Bereich dicht durchsetzt. Die laterale Ausdehnung derp ⁺-Gebiete zwischen denp-Teillen sowie das vertikale Dotierungsprofil desp-Bereichs werden so, gewählt, daß der hohe Emitterwirkungsgrad desp ⁺-Bereichs erst bei hohen Strömen wirksam wird und die Durchlaßspannung verkleinert. Bis zum üblichen betriebsmäßigen Durchlaßstrom ist die Ladungsträgerkonzentration an der Anodenseite der Basis kleiner als amnn ⁺-Übergang. Dies führt beim Kommutieren zu einer starken Verkleinerung der Rückstromspitze und einem wesentlich weicheren Abfall des Rückstroms (Soft-Recovery-Verhalten) als bei üblichen schnellen Dioden gleicher Durchlaß- und Sperrspannung. Simulationsrechnungen wie auch Meßergebnisse zur Wirkungsweise und zum Schaltverhalten werden vorgestellt.

     

相复励旋硅式无刷同步励磁电机旋转二极管的故障监测

分析了相复励旋硅式无刷同步励磁电机旋转二极管的开路和短路状态，并以某大功率中速柴油发电机组为例，分析了其旋转二极管监测电路框图的工作原理，该监测电路在二极管开路时能延时发出信号，而在二极管短路时能迅速解列发电机，以维护机组的安全。最后对监测电路的实际性能进行了简要的说明和探讨。     

Active tracker laser (ATLAS)

A high brightness diode-pumped, Nd-YAG solid state laser has been designed, fabricated, and tested. This phase conjugated master oscillator/power amplifier (MOPA) device produces 20-ns Q-switched pulses at 2500 Hz at an average power of 690 W and a beam quality of 1.1×DL when the pump diodes are operated at 27.5% duty cycle. With an external KTP doubler, this device has produced 175 W of green average power at a beam quality of 1.5 × DL and a conversion efficiency of 45% over continuous operating times as long as one hour. This 1.06 μm result is believed to be the highest average power brightness achieved, and the 532-nm performance is both the highest average green power and the highest average brightness ever reported     

HIS高集成开关设备的应用

全新设计的高集成开关设备由于其体积紧凑，可靠性高而得到了用户的欢迎，本文介绍了该产品两个变电站成功运行的例子。     

配电网智能监控管理远程抄表一体化系统

针对广大中小城镇和农村配电网的现状、存在问题和需求,研发了配电网智能监控管理远程抄表一体化系统,由配电主站、配电子站、配电终端、通信系统等组成.介绍了该系统的网络结构,并详细介绍各组成部分的功能和特点.配电主站集成了配电SCATA、配电管理、设备管理、远程抄表、故障诊断和故障报警以及配电GIS等综合功能.一体化系统实用性强、可节约用户投资、便于管理.该系统已成功地投入运行,实践证明应用该系统可提高供电企业的运行管理水平和自动化水平、提高服务质量,可取得明显的经济效益和社会效益.     

Response speed and optical investigation of inGaN/gaN multiple quantum well light‐emitting diodes (LED)

Transmission experiments for a local area network (LAN) using blue‐light‐emitting diodes (LEDs) with InGaN/GaN multiple quantum well (MQW) and plastic optical fibers (POFs) have been conducted. Audio analog signals have been transmitted up to 1800 kHz, which corresponds to an optical 1.5 dB bandwidth of LED response. The response speed of these diodes has been investigated by varying the operating conditions: dc bias, pulse amplitude, and pulse shape. The LED rise time is reduced from 0.26 μs to 0.19 μs by changing the electrical pulse amplitude from 0.5 V to 1.2 V, whereas the fall time (0.20 μs) does not change. On the other hand, the fall time is reduced from 0.20 μs to 0.14 μs by adding negative pulses after the applied positive pulses. It is shown that the direct‐modulation speed of these diodes is limited by the time constant associated with device capacitance. Electroluminescence and photocurrent spectra of the LEDs were also investigated; blueshifts were observed for both peaks in the spectra. © 2001 Scripta Technica, Electr Eng Jpn, 137(3): 47–51, 2001     

Receiver autonomous integrity monitoring (RAIM) performances of combined GPS/BeiDou/QZSS in urban canyon

Multi‐GNSS (global navigation satellite system) has become a trend to solve the urban canyon effect in order to meet the requirements of GNSS users, but the probability of mistaken satellites is also increasing with the increase in the number of visible satellites. The receiver autonomous integrity monitoring (RAIM) performance has therefore become very important. In this paper, the minimum RAIM availability (MRA) is proposed to evaluate the RAIM availability of combined GNSS constellations, and the minimal detectable effect (MDE) is applied to assess the RAIM fault detection capability. The significant improvements of RAIM performances in urban canyons when GPS/QZSS (quasi‐zenith satellite system) are combined without and with BeiDou are quantified and analyzed by the simulations of the Asia‐Pacific region snapshot and temporal variations in Beijing, Tokyo, Shanghai, and Hong Kong with different masking angles. The combining of BeiDou with GPS/QZSS has great realistic significance, especially in the Asia‐Pacific region. The evaluation measure of RAIM performances can be used to predict the availability of GNSS constellations under different conditions, and it can be also used to assess the availability and integrity of combined constellations. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

HEV用稀土永磁ISG功率变换器拓扑及其控制

混合动力电动汽车(HybridElectricVehicle简称HEV)技术是当前国际上的研究热点,组合起动/发电机(IntegratedStarter/Generator简称ISG)是HEV的重要部件。针对770N·m起动转矩的稀土永磁ISG,设计了可变结构的功率变换器拓扑。在相应的稀土永磁电机设计和控制器设计基础上,实现了功率变换器的串联和并联切换,以解决低速大扭矩起动转矩问题和高速发电电压的可控性问题。讨论通过1.2kA电流的功率器件的并联问题,分析了状态控制方法,给出了数字控制器控制框图。     

Experimental study on the intrinsic response, optical and electrical parameters of 1.55-/spl mu/m DFB BH laser diodes during aging tests

This paper reports on an investigation on the light-current, relative intensity noise, and chirp variations of life-tested InGaAsP/InP multiquantum-well buried heterostructure (BH) laser diodes (LDs). The devices have been stressed at highly accelerated aging conditions (I=170 mA, T=140/spl deg/C for 3000 h). Typically, the operating current at constant output optical power (I/sub op/) increases logarithmically with time in stable devices while the noise resonance frequency remains stable. High-frequency RF signal-induced chirp for relative stable LDs at constant output power shows very little change with time.