简单的激光窄脉冲信号准峰值采样保持电路

介绍了一种能完成高速采样保持功能的电路，与一般的准高速采样保持电路相比，后者采样时间长，不能满足激光窄脉冲信号的采样要求。国外高速采样保持集成电路器件价格昂贵、体积较大、使用不便，难以普及应用。准高速采样保持电路响应时间短、电路简单、成本低、能较好地满足峰值存贮的要求。通过电路试验和整机试验证明电路是可行的。     

高功率窄脉冲垂直腔面发射激光器n-DBR反射率的优化

从理论上研究了n型分布布拉格反射镜(n-DBR)的反射率对器件阈值电流、输出功率以及转换效率的影响,得出了最佳反射率。在此基础上研制了垂直腔面反射激光器(VCSEL)单管和阵列器件,采用波形分析法对VCSEL器件的功率进行了测试。在脉冲宽度60ns,重复频率100Hz条件下,500μm口径单管器件在注入电流为110A时,峰值输出功率达102W,功率密度为52kW/cm2,4×4、5×5阵列器件在100A时,功率分别达到98W和103W。对比了单管器件在连续、准连续和脉冲工作条件下的输出特性和光谱特性,连续和准连续条件下激射波长的红移速率分别为0.92nm/A和0.3nm/A,6A时的内部温升分别为85℃和18℃,而脉冲条件下激射波长的红移速率仅为0.0167nm/A,6A时的温升为1.5℃,远小于连续和准连续的情况,这也是器件在脉冲条件下能得到很高输出功率的主要原因。     

迫弹激光引信用脉冲半导体激光电源的设计与应用

设计了适应于迫弹激光近炸引信的小体积、低电压、窄脉宽、高功率的脉冲半导体激光电源.采用电容充放电的模式,选用高速大功率MOSFET管作为开关,设计了相应的高速开关控制电路.激光电源模块的重复频率高达50kHz,常规热电池供电电压条件下的输出脉冲激光峰值功率为9W,光脉冲上升沿为4.2 ns,光脉宽为10 ns,为有效提...     

窄脉冲激光探测电路分析与设计

光电检测电路的设计对激光探测系统的性能有重要的影响。针对窄脉冲激光的时域特性,对窄脉冲激光电路设计进行了详细的分析,包括光电二极管的偏置电压对检测电路的影响、光电流转换方式对信号带宽影响等。为提高探测系统信噪比,对放大电路、补偿电路的带宽设计提出优化方法,给出窄脉冲激光探测器的前级放大电路参数设计的依据,并对探测电路优化及设计方法进行了详细论述,为光电检测电路的设计提供了有效的设计方法。     

脉冲激光近炸引信鉴相体制实验误差的研究

鉴于目前国内脉冲式激光定距系统的精度较低,小于1米,因而不能满足许多场合的需要,如云爆弹定距等。本文在参考大量文献的基础上,经过反复试验仿真,总结出了影响脉冲式激光定距体制的几个因素,并且提出了解决问题的措施。     

窄脉冲激光信号峰值保持电路设计

首先介绍了跨导型峰值保持电路的结构和原理,使用两种不同的跨导放大器,设计了适用于窄脉冲激光信号的跨导型峰值保电路,通过仿真分析后选择其中一种最合适的放大器进行电路实验,并通过实验详细讨论了影响电路保持效果的各项因素。该电路具有结构简单、线性良好、保持精度高等特点。     

基于雪崩效应的小型激光激励源电路研究

为了获得高功率、窄脉冲探测激光,提出了一种基于雪崩效应的小型半导体激光激励源电路实现方案,分析了激励电路产生高压窄脉冲信号的原理,介绍了其组成单元信号整形电路、直流偏置电路和高压脉冲产生电路的硬件设计。测试表明,该电路能够输出电压约460V、脉宽小于6.0ns、下降沿约2.5ns的脉冲激励信号,印证了原理设计的正确性。该电路具有高性能、小体积、高可靠和易适装的应用特点,能够有效满足某激光引信对激光激励电路的任务要求。     

激光光电窄脉冲信号峰值检测器

介绍一种新型窄脉冲峰值检测器，这种检测器采用非线性反馈结构，实现ｎｓ脉冲的峰值检测，它主要的特点是非线性小，检测动态范围宽，输出信号随脉冲形状与脉宽的变化小。     

窄脉冲高功率激光光纤耦合技术研究

研究了实心圆锥形光锥和光纤截面的各种曲面的几何成像原理,利用光锥会聚光能的作用降低会聚光功率密度,采用球面光纤头,扩大光纤接收光能的面积.使激光光束垂直于光锥大端入射,40～50%的激光直接射出小端,其余激光在光锥内发生一次全反射射出小端.光纤头球面贴近小端同轴放置,使进入光纤的光线入射角大于光纤的全反射临界角,从而实现窄脉冲高功率激光的光纤耦合. 文中对圆锥形光锥和光纤头球面的参数进行计算.由传输光束的截面和光纤纤芯尺寸选取小端直径,使它略小于光纤纤芯直径,根据光纤数值孔径确定光锥顶角和光纤球面曲率半径. 实验采用固体YAG高重复率电光调Q激光输出,平均功率30 W,光束直径Φ6 mm,光纤纤芯直径Φ0.6 mm,实心圆锥形光锥小端直径Φ0.4 mm,光锥顶角24°,材料折射率1.52,光纤耦合效率75%.(PG10)     

A high-power short-pulse laser diode for waveguide second harmonic generation

This paper describes successful development of a high-power short-pulse i.r. laser diode, together with numerical analyses giving a clear understanding of the operation. The novel aspect of the present laser diode is that a saturable absorber is incorporated for gain switching into the buried-twin-ridge substrate (BTRS) structure which allows a high-stability fundamental spatial mode operation. Peak powers as high as 1.23 W and pulse widths as narrow as 34.1 ps have been obtained in an efficient gain-switching operation with the high mode stability. The experimental observations are well-explicable by the numerical analyses in substantial respects. We also report picosecond-pulse blue-light generation which has been attained by applying the frequency doubling technique to the above laser in a LiNbO₃ waveguide.     

光纤激光作为激光武器的能力分析

简要介绍了高功率光纤激光的发展,分析了双包层光纤激光器作为激光武器的可能性,并给出了实现高能单模激光输出的主要技术方案。     

高能脉冲氙灯驱动电路特性分析

为了增强高能脉冲激光器的驱动效能、优化驱动电路的工程实现效果,采用电路分析与仿真的方法,对脉冲氙灯和脉冲形成网络的放电特性进行了理论分析和仿真验证,取得了各影响因素与脉冲电流波形的相关度数据.结果表明,脉冲电流波形的矩形度和工程实现的难度随节数的增加而增加,理想节数在5附近;波峰幅值随末链电感的减小而减小,其加权值的理...     

Analysis of a dual grating-type surface emitting laser

The grating-coupled surface emitter (GSE) consists of a gain section between two grating sections, which are not necessarily identical. The gratings act as both distributed Bragg reflectors and output couplers. An analysis that applies to arbitrary grating shapes and has provisions to include the presence of a substrate reflector to reduce the radiated power into that medium is carried out. Thresholds, differential efficiencies, and far-field patterns are compared for the low-threshold longitudinal modes of the system. Examples illustrating variations in tooth shapes and heights, waveguide loss, the presence of a substrate reflector, and detuning from the Bragg condition are included     

Low threshold high-power room-temperature continuous-wave operation diode laser emitting at 2.26 /spl mu/m

Diode lasers emitting at 2.26 /spl mu/m, based on the InGaAsSb-AlGaAsSb materials system, are reported. These devices exhibit high internal quantum efficiency of 78% and low threshold current density of 184.5 A/cm/sup 2/ for a 2-mm-long cavity. Output power up to 700 mW (/spl ap/550 mW) has been obtained at 280 K (300 K) in continuous-wave operation with 100 /spl mu/m/spl times/1 mm lasers. These devices have been coated with an antireflection on the output facet and are mounted epilayer down on a copper block. The working temperature was maintained by a thermoelectric Peltier cooling element.     

Junction temperature and reliability of high-power flip-chip light emitting diodes

In this work, infrared micro-imaging, emission microscope measurements are performed on the chip surface of flip-chip light emitting diodes (FCLEDs). The temperature deviation on the chip surface increases from 19 to 146 °C when the injection current changes from 20 to 2000 mA. When the structure of FCLED is optimized, the temperature deviation becomes smaller. And the thermal resistance is achieved to as low as 10.4 °C/W. The finite element method calculation based on the model of steady-state current field and temperature field is carried out to investigate the effects of current spreading on thermal performance of FCLED.     

Kinetic issues for short-pulse KrF laser operation

Various kinetic issues that are important for modeling the performance of large-scale-size krypton fluoride lasers have been investigated. These kinetic issues include: electron quenching, photoionization from excited rare gas atoms, fuel burn-up, and the accessibility of higher lying levels of KrF* to be effectively stimulated by the laser cavity flux. The results of these studies have been incorporated into a laser kinetics code. Absorption and gain measurements have been carried out over a broad range of conditions to provide a data base to test the code's accuracy and to make subsequent refinements. The code projections for short-pulse operating conditions important for laser-fusion applications are presented.     

Failure and degradation mechanisms of high-power white light emitting diodes

The investigation explores the factors that influence the long-term performance of high-power 1 W white light emitting diodes (LEDs). LEDs underwent an aging test in which they were exposed to various temperatures and electrical currents, to identify both their degradation mechanisms and the limitations of the LED chip and package materials. The degradation rates of luminous flux increased with electrical and thermal stresses. High electric stress induced surface and bulk defects in the LED chip during short-term aging, which rapidly increased the leakage current. Yellowing and cracking of the encapsulating lens were also important in package degradation at 0.7 A/85 °C and 0.7 A/55 °C. This degradation reduced the light extraction efficiency to an extent that is strongly related to junction temperature and the period of aging. Junction temperatures were measured at various stresses to determine the thermal contribution and the degradation mechanisms. The results provided a complete understanding of the degradation mechanisms of both chip and package, which is useful in designing highly reliable and long-lifetime LEDs.     

Ku-band high-power amplifier MMIC with on-chip gate biasing circuit

A new active bias scheme for GaAs HEMT high-power amplifier (HPA) MMICs is proposed that compensates variation of gate threshold voltage and temperature. The quiescent currents of the amplifier were estimated within ±0.7% when the threshold voltage varied from -0.3 to 0.3 V. Also, the measured quiescent currents were increased with temperature, providing compensation of temperature variations. A Ku-band HPA, using 0.5 νm GaAs pHEMT processes, was fabricated to demonstrate the suggested bias topology.