高功率半导体量子阱激光器测试中的灾变性损伤

在使用综合参数测试仪测试808nm发射的半导体量子阱激光器的过程中，出现了一种由电浪涌所导致的灾变性损伤。通过测试的功率曲线和伏安特性曲线，断定激光器出现了灾变性的损伤，同时测试的发射光谱不再是激射光谱，而是由自发辐射所产生的荧光光谱。由扫描电镜(SEM)观察到了激光器的腔面膜出现了熔化，证实激光器的确发生了灾变性损伤。作为对比，我们引用了另一种在测试中发现的快速退化现象，对两种退化出现的原因进行了理论上的分析，了解到激光器的退化主要还是由器件本身的材料、结构以及后期的工艺过程所决定的，在测试器件过程中电浪涌只不过会加速或产生突然灾变性退化。通过测试我们建立了一种比较简单的检验一个激光器质量可靠性的方法，所以理解由电浪涌所引起的退化行为是非常重要的。     

基于LabVIEW的高分辨率光谱测试系统(英文)

提出了一种基于LabVIEW的无源器件光谱测试方案.通过LabVIEW编程控制可调谐激光器、可编程光滤波器、光功率计和数据采集平台,获得了具有不同传递函数的光谱特性.实验中激光器的扫描速度为10nm/s,扫描范围为10nm,数据采集卡的采样速率为1MS/s,结果表明:单个器件的光谱测试可以在1s内完成,光谱分辨率可达1pm;与利用宽带光源和光谱分析仪的传统光谱测试方法相比,所提方案的测试性能可达到传统方案水平,且能显示更精细的光谱细节.该方案能应用于有高分辨率、快速和高效要求的光谱测试中.     

电子式电流互感器中的供能激光器退化机理研究

电子式电流互感器中的供能激光器是给远端模块供能的半导体器件。为了解决其故障频发的问题,需要研究其退化机制从而为器件可靠性提升提供可行思路。设计了一套半导体激光器外特性综合测试系统,利用恒温加热箱、振动台可测得在不同温度、振动下的激光器的PIV曲线、波长等外特性参数,并通过相关性分析,表明缓慢退化的关键参数与环境敏感参量的影响机制。其次,对故障光芯片进行失效表征得出供能激光器退化机理。最后对不同退化程度的激光器光功率进行指数拟合得到供能激光器在工况条件下的预期寿命为127 438 h,并给出运维改进措施。研究结果表明退化后的激光器斜率效率变化最为显著可达7.99%,阈值电流变化为4.98%,两参量与激光器退化呈现强相关;而芯片退化乃至失效原因主要为腔面膜层损伤不断加剧导致腔面发生光学灾变。     

GaN基白光发光二极管失效机理分析

对小功率白光GaN基发光二极管(LED)在室温、40 ℃和70 ℃下进行温度加速老化寿命实验,通过对老化前后不同时间段器件的电学、光学和热学特性进行测量来分析器件的失效机理,着重分析器件的芯片和荧光粉的失效机理.器件老化前后的I-V特性表明:老化过程中,器件的串联电阻和低正向偏压下的隧道电流增大,这是由于器件工作时其芯片的欧姆接触退化和半导体材料的缺陷密度升高而引起的.器件的热特性表明:高温度应力下器件的热阻迅速变大,封装材料迅速退化,这是器件退化的主要原因;光谱曲线表明温度加速了器件的     

基于Nd∶YVO_4晶体四波段腔面膜的研制

黄光激光器作为一种接近人眼敏感区域的激光器在诸多领域都发挥着重要的作用,而谐振腔又是激光器中重要组成部分.本文以Nd∶YVO4(c-cut)晶体为基底,利用真空镀膜设备研制出四波段腔面膜.通过分析膜系设计过程中膜层电场强度和优化膜系,使膜层中驻波场强得到合理分布,从而在理论上减小膜层损伤的可能性;通过TFCalc软件对测试结果进行工艺反馈分析,经过多次模拟实验,发现在不同控制波长下,采用相同监控方法监测不同的膜厚比例系数,通过调整工具因子解决了光谱曲线漂移的问题,制备出膜层牢固、化学性能稳定、满足四个波段光谱输出的黄光激光器腔面膜.     

1.06 μm InGaAs/InGaAsP量子阱半导体激光器的温度特性

研究了1.06 μm InGaAs/InGaAsP量子阱半导体激光器厘米bar模块的温度特性,测试分析了该模块的输出光功率、阈值电流、转换效率和光谱随注入电流及管芯温度变化的特性。结果表明,器件在15~55 ℃范围内所测的输出光功率由40.7 W降低到29.4 W,阈值电流由9.29 A升高到17.24 A,转换效率由54.22%降低到37.55%,光谱漂移为0.37 nm/℃,特征温度为68.6 K。实验结果表明,为保持器件性能的稳定,在实际应用过程中应该使器件的温度控制在15~25 ℃范围内。     

785nm便携式光栅外腔可调谐半导体激光器的研制和输出特性

针对移频激发拉曼光谱测试系统的小型化需求,在Littrow结构中,采用商用的785nm大功率激光二极管作为增益器件,构建了一款便携式光栅外腔可调谐半导体激光器。该激光器通过采用一种新型的波长调谐方法,即以改变半导体增益器件相对于准直透镜的水平位置来实现波长的连续调谐,实现了尺寸为140mm×65mm×50mm的小型化结构设计。相比于传统的旋转衍射光栅改变光线在光栅上的入射角来实现波长调谐的方式,该方法有效地缩减了增益器件的平移距离,从而有利于便携式外腔激光器波长的快速宽带调谐。实验结果表明,该激光器具有较宽的波长调谐范围,在340~900mA注入电流下均可实现10nm以上的波长调谐,尤其在900mA大注入电流下,其波长调谐覆盖779.40~791.07nm,调谐范围可达11.67nm,且激射线宽小于0.2nm,单波长输出功率最高可达280mW,放大的自发辐射抑制比大于25dB,呈现出较优异的输出性能,满足移频激发拉曼光谱检测系统对光源的基本要求。此外,该激光器可采用一微型压电陶瓷驱动器来实现波长的电动调谐,实验获得了1.35nm的波长调谐范围,证实了所制785nm便携式光栅外腔可调谐半导体激光器适合作为便携式移频激发拉曼光谱检测系统的光源用于减除原始拉曼光谱中的荧光背景。     

对导质结激光器和发光二极管退化的评论

把异质结用在半导体激光器和高亮度发光二极管,大大地改善了器件的性能。然而,由于早期器件的寿命不稳定,可靠性便是主要关心的问题。现在,可靠的器件已经生产了,这是由于广泛地研究退化的原因和避免方法的结果。激光器的可靠性由两种基本因素来控制,即镜面损伤和内部形成非辐射中心。     

808nm高功率半导体激光器的低频电噪声及其与器件质量的相关性

在不同条件下测试了808nm高功率单量子阱半导体激光器的低频电噪声和器件的电导数（Id/dI-I）特性。讨论了噪声和器件质量的相关性,结果表明,808nm高功率半导体激光器的低频电噪声主要为1／f噪声,且与器件质量有着较好的相关性。     

CMOS反相器的快上升沿强电磁脉冲损伤特性（英文）

随着电磁环境的日益复杂,保证集成电路(IC)的可靠性成为一个巨大的挑战。在此基础上,通过对CMOS反相器的仿真和实验研究,研究了快上升沿电磁脉冲(EMP)引起的陷阱辅助隧穿(TAT)效应。对此进行了详细的机理分析用于解释其物理损伤过程。EMP感应电场在氧化层中产生陷阱和泄漏电流,从而导致器件的输出退化和热失效。建立了退化和失效的理论模型,以描述输出退化及热积累对EMP特征的依赖性。温度分布函数由半导体中的热传导方程导出。基于TLP测试系统进行的相应实验证实了出现的性能退化,与机理分析一致。Sentaurus TCAD的仿真结果表明,EMP引起的损坏是由栅极氧化层中发生的TAT电流路径引起的,这也是器件的易烧坏位置。此外,还讨论了器件失效与脉冲上升沿的关系。本文的机理分析有助于加强其他半导体器件的EMP可靠性研究,可以对CMOS数字集成电路的EMP加固提出建议。     

新型多有源区隧道再生光耦合大功率半导体激光器

针对大功率半导体激光器面临的主要困难,提出并实现了一种隧道再生多有源区耦合大光腔 高效大功率半导体激光器机理.该机理能有效地解决光功率密度过高引起的端面灾变性毁坏 、热烧毁和光束质量差等大功率激光器存在的主要问题.采用低压金属有机化合物气相淀积 方法生长了以碳和硅作为掺杂剂的GaAs隧道结、GaAs/InGaAs 应变量子阱有源区和新型多有 源区半导体激光器外延结构,并制备了高性能大功率980nm激光器件.三有源区激光器外微分 量子效率达2.2,2A驱动电流下单面未镀膜激光输出功率高达2.5W. 关键词： 半导体激光器 大功率 金属有机化合物气相沉积     

High power AlGaInP laser diodes with zinc-diffused window mirror structure

The technology of zinc-diffusion to improve catastrophic optical damage (COD) threshold of compressively strained GaInP/A1GaInP quantum well laser diodes has been introduced. After zinc-diffusion, about 20-μm-long region at each facet of laser diode has been formed to serve as the window of the lasing light. As a result, the COD threshold has been significantly improved due to the enlargement of bandgap by the zinc-diffusion induced quantum well intermixing, compared with that of the conventional non-window structure. 40-mW continuous wave output power with the fundamental transverse mode has been realized under room temperature for the 3.5-μm-wide ridge waveguide diode. The operation current is 84 mA and the slope efficiency is 0.74 W/A at 40 mW. The lasing wavelength is 656 nm.     

A Novel Kind of Transverse Micro-Stack High-Power Diode Bars

Novel transverse micro-stack semiconductor laser bars are put forward to improve the output optical power of semiconductor laser bars at low injection current. More importantly, the novel laser bars have a coupled large optical cavity, which can overcome the problem of catastrophic optical damage and improve light beam quality due to the coherently coupled emitting along the transverse direction. The micro-stack tunnel regeneration tri-active region laser structure was grown by metal organic chemical vapour deposition. For a weakly coupled uncoated device, the optical power exceeds 60 W under 50 A driving current and the slope efficiency reaches 1.55 W/A. Further experiments show that the perpendicular divergence of 23° is achieved from transverse strongly coupled devices.     

Multiple quantum well structures and high-power lasers of gaas- algaas grown by metalorganic vapor phase epitaxy (MOVPE)1

GaAs/AlGaAs GRIN-SCH type multiple quantum well lasers with four wells of 11 nm GaAs, grown in an MOVPE chimney reactor, exhibit an output power as high as 110 mW/facet (CW, 30°C; 5 μm stripe) and 1.3 W/facet (pulsed, 30°C; 53 μm stripe) until catastrophic optical damage occurs. 2000 hours life tests conducted at 60°C and 15 mW CW show no noticeable degradation for the 5 μm stripe laser with a reflective coating on both facets. Raman spectroscopy on similar multiple quantum well structures with 65 GaAs wells is used to ascertain that the wells have minimum residual aluminum- content.     

Stable high optical power in quantum well lasers with profiled reflection and tapered structures

A comprehensive model is presented to study quantum well tapered lasers and quantum well stripe lasers with profiled reflectivity output facets and to obtain lateral stability in high power semiconductor laser. Simulation of semiconductor lasers is performed by numerically solving space-dependent coupled partial differential equations for the complex optical forward and backward waves, carrier density distribution and temperature distribution. The coupled equations are solved by finite difference beam propagation method. The effect of nonlinear parameters like Kerr and linewidth enhancement factors, and precise dependence of linewidth enhancement factor and gain factor on the carrier density and temperature are considered in this paper. We use modal reflector in stripe lasers to confine the lateral mode to the stripe centre and provide the stable operation. We also use unpumped window to reduce the facet temperature and improve the catastrophic optical mirror damage level of tapered lasers.     

Multiple quantum well structures and high-power lasers of gaas- algaas grown by metalorganic vapor phase epitaxy (MOVPE)1

GaAs/AlGaAs GRIN-SCH type multiple quantum well lasers with four wells of 11 nm GaAs, grown in an MOVPE chimney reactor, exhibit an output power as high as 110 mW/facet (CW, 30°C; 5 μm stripe) and 1.3 W/facet (pulsed, 30°C; 53 μm stripe) until catastrophic optical damage occurs. 2000 hours life tests conducted at 60°C and 15 mW CW show no noticeable degradation for the 5 μm stripe laser with a reflective coating on both facets. Raman spectroscopy on similar multiple quantum well structures with 65 GaAs wells is used to ascertain that the wells have minimum residual aluminum- content.     

Performance evaluation of VCSEL through single and multi mode fibers

This paper presents influence of the change in temperature of a vertical cavity surface emitting laser (VCSEL) on its output power. It is observed that with increase in temperature of laser its output power decrease. It is also observed that with decrease in threshold voltage of the laser output power increase. Decrease in output power due to increase in temperature can be compensated by increasing driving current. But increase in drive current decrease life of the laser. So a laser with lower threshold voltage can be used to operate at high temperature with long life. Propagation of VCSEL through single mode and multimode fiber is also studied. In single mode fiber only one propagation mode exists due to which signal can be transmitted to longer distances.     

Reliability study on high-power 638nm broad stripe laser diode

High-power laser diodes (LDs) are strongly demanded as a light source of display applications. In this work, the reliability of a high-power 638 nm broad stripe (BS) LD was studied from the viewpoint of not only gradual degradation but also catastrophic optical degradation (COD) at a front facet. Long term acceleration aging tests for the 638 nm BS-LD with the window-mirror structure by using Zn diffusion were performed. It was confirmed that COD only occurs at a high output power and this mode was dominant compared with gradual degradation. The result also revealed that the mean time to failure due to COD was proportional to optical density to the power of ?3:2. It is clarified that maintaining a low optical output power density is essential to develop high-power and highly reliable red BS-LDs.     

A CW CO2 laser using a high-voltage Dc–dc converter with resonant inverter and Cockroft–Walton multiplier

I propose a high-voltage Dc–dc converter for a CW (continuous wave) CO₂ laser system using a current resonant half-bridge inverter and a Cockcroft–Walton circuit. This high-voltage power supply includes a two-stage voltage multiplier driven by a regulated half-bridge series resonant inverter. The inverter drives a step-up transformer and the secondary transformer is applied to the voltage multiplier. It is highly efficient because of the reduced amount of switching losses by virtue of the current resonant half-bridge inverter, and also due to the small size, low parasitic capacitance in the transformer stage owing to the low number of winding turns of the step-up secondary transformer combined with the Cockroft–Walton circuit. I obtained a maximum laser output power of 44 W, a maximum system efficiency of over 16%, and the stability of laser output power of about 4.6% in this laser system.     

A tunnel regenerated coupled multi-active-region large optical cavity laser with a high quality beam

A novel coupled multi-active-region large optical cavity structure cascaded by a tunnel junction is proposed to solve the problems of facet catastrophic optical damage (COD) and the large vertical divergence caused by the thin emitting area in conventional laser diodes. For a laser with three active regions, a slope efficiency as high as 1.49 W/A, a vertical divergence angle of 17.4 , and a threshold current density of 271 A/cm 2 are achieved. By optimizing the structural parameters, the beam quality is greatly improved, and the level of the COD power increases by more than two times compared with that of the conventional laser.