半导体激光器退化和寿命评价

近年来半导体激光器(LD)的应用和性能的提高令人注目。目前激光器行业中,多数产品都是半导体激光器,其以效率高,结构紧凑寿命长等独特的优点在光通信,国防及医疗等方面得到了极其广泛的应用,并且随着激光器件技术的发展,大功率半导体激光器将逐步成为光通信,激光器泵浦等应用中的     

半导体激光器的新秀--微碟激光器

主要概述国内外半导体微碟激光器的发展现状以及制备技术。     

基于二元混合随机过程的轴承剩余寿命预测

针对轴承退化问题,基于两个不同变化特点的性能指标,提出了基于二元混合随机过程的轴承剩余寿命(RUL)预测方法。首先,分析两个特点不同的性能指标,选择合适的随机过程(伽马过程或维纳过程)分别构建基于不同性能指标的退化模型;其次,利用Copula函数分析两个性能指标间的相关特性并构建剩余寿命的联合概率密度函数;然后采用分步极大似然估计法在线更新模型参数,预测未来时刻的剩余寿命;最后,通过仿真和轴承实验数据对所提方法进行验证分析。结果显示所提方法能有效地预测轴承的剩余寿命,通过与基于一元随机过程的剩余寿命预测方法的对比分析,发现所提方法具有更好的预测精度。     

半导体温差电元件接触性能的评估

半导体温差元件接触电阻和接触热阻是影响器件性能的重要参数，它们在很大程度上器件制备工艺水平的反映。根据元件温差发电输出功率与元件电偶臂长度的相互关系模型，可以简单地通过测量系列化元件的开路电压和短路电流对接触特性作出评估。实测了两种不同来源的半导体制冷器以说明其实际应用。     

TNT基炸药储存寿命评估研究?

为解决有效评估炸药储存寿命的难题,提出一套基于炸药加速退化试验失重率阈值的储存寿命评估技术。采用基于伪失效寿命的加速寿命试验数据建模与处理方法,对某TNT基炸药加速退化试验数据,使用正态分布和威布尔分布模型,估计了两种模型参数,评定了其储存寿命。研究表明,该评估技术可行,结论可信。     

半导体激光器的高精度温度控制优化设计

温度对半导体激光器(LD)发射器的特性有较大的影响,随着温度的增加,阈值电流呈指数增加,输出功率和斜率分别呈抛物线和指数关系递减,同时特征温度也减少,波长随温度的漂移系数为0.24nm/℃[1]。为了使半导体激光器的激光波长和输出功率稳定,必须对其温度进行高精度的控制。利用积分分离式PID控制原理设计了温度控制系统,控制精度达到±0.1℃,与普通PID控制器相比,极大的提高了系统的瞬态特性。     

外腔激光器光子寿命对波长转换特性的影响

作为自动交换光网络中的核心器件,全光波长转换器发挥着重要作用。本文根据光纤光栅外腔半导体激光器(FBG-ECL)实现波长转换的理论模型,重点研究光子寿命对波长转换器调制特性的影响;利用速率方程,数值求解了不同光子寿命下波长转换特性;通过自行搭建的基于FBG-ECL的实验平台进行了实验分析,发现理论分析和实验数据是吻合的。     

半导体激光器的高精度温度控制优化设计

温度对半导体激光器(LD)发射器的特性有较大的影响,随着温度的增加,阈值电流呈指数增加,输出功率和斜率分别呈抛物线和指数关系递减,同时特征温度也减少,波长随温度的漂移系数为0.24nm/℃[1].为了使半导体激光器的激光波长和输出功率稳定,必须对其温度进行高精度的控制.利用积分分离式PID控制原理设计了温度控制系统,控制精度达到±0.1℃,与普通PID控制器相比,极大的提高了系统的瞬态特性.     

空间用斯特林制冷机的寿命评价

介绍了空间用斯特林制冷机的主要失效模式和失效机理,国内外寿命评价研究的状况和进展,分析了几种加速寿命评价方法.针对中国空间用制冷机寿命评价研究的现状,提出了加速寿命评价的一些见解和思路.     

Discrete-event stochastic systems with correlated inputs: Modeling and performance evaluation

In the majority of the previous works on discrete-event stochastic systems, they have been assumed to have independent input processes. However, in many applications, these input processes can be highly correlated. Furthermore, the performance measures of the systems with correlated inputs can be significantly different from those with independent inputs. In this paper, we provide an overview on some commonly used methods for modeling correlated input processes, and we discuss the difficulties and possible future research topics in the study of discrete-event stochastic systems with correlated inputs.     

A route instrument for measuring the concentration of gases based on a two-wavelength semiconductor laser

A route instrument for measuring small concentrations of gases which uses as the radiation source a semiconductor laser diode with an asymmetrical quantum-dimensional heterostructure is considered. Optoelectronic recirculation simultaneously at two optical wavelengths is achieved in the system, which enables the accuracy of route measurements of the concentration of gases to be achieved and also enables the length of the monitored route to be measured. __________ Translated from Izmeritel’naya Tekhnika, No. 1, pp. 64–67, January, 2007.     

半导体激光器后腔面高反射涂层的研究

采用金属银(Ag)做为高反射镀膜材料，ZrO2介质膜作为与激光器端面的绝缘层和Ag保护膜，在激光器后腔面实现了高反射涂层。经激光器光电特性测试表明，该高反射膜系能使激光器输出功率提高60％，阈值电流减小20％～50％，并且具有良好的化学稳定性、热稳定性和机械强度，能有效保护半导体激光器后腔面。     

隧道再生大功率半导体激光器模式特性分析

利用有效折射率法计算了隧道再生双有源区大功率半导体激光器的工作模式,并对计算得到的激射模式的近场、远场与实验结果进行比较,得到激射模式为一阶模,二者十分吻合,这有助于进一步优化设计波导结构。     

Engineering‐driven performance degradation analysis of hydraulic piston pump based on the inverse Gaussian process

As a key aircraft component, hydraulic piston pumps must be developed with high reliability. However, collecting failure time data of such pumps for reliability analysis is a big challenge. To save testing time, performance degradation data obtained from degradation tests can be used for quick reliability estimation of hydraulic piston pumps. This paper proposes an engineering‐driven performance degradation analysis method considering the nature of mechanical wear of hydraulic piston pumps. First, the failure mechanism of a type of hydraulic piston pump is investigated. By taking into account the close relationship between the degradation rate and the failure mechanism, an inverse Gaussian (IG) process model with a variable rate is developed to describe the degradation behavior of the pump. Under this model, a Bayesian statistical method is developed for degradation data analysis. The corresponding procedure for model parameter estimation and reliability evaluation is also presented. The proposed degradation analysis method is illustrated using a real experimental data. The results show that the engineering‐driven approach is quite effective in evaluating the lifetime of the hydraulic piston pump and will improve the overall reliability of aircraft operation in the field.     

半导体激光器恒温控制系统的高精度温度测量研究

 半导体激光器性能受温度影响较大,为了提高其工作稳定性,设计了一个应用于半导体激光器的恒温控制系统.该系统由05 mA恒流源对Pt100温度传感器供电,采用四线制测量方法获得精确的温度信号.应用TLC2652斩波放大器设计前置放大器,并采用差分放大电路对信号进行后续比较放大.使用半导体制冷器(TEC)制冷,实现系统的恒温控制.经实验数据分析可以看出,该恒温系统可有效地工作,温度控制偏差最大为±002 ℃.通过调节相应参数,可自由设定恒温系统的温度值,应用于不同温度控制环境.     

大功率半导体激光器热沉结构的数值模拟

为了提高激光器的冷却效果,设计了3种具有不同扩展结构的热沉,包括矩形平行肋、菱形肋片和30°矩形斜肋,模拟计算3种结构对应的热沉芯片的最高温度、器件热阻和水泵功耗。结果表明30°矩形斜肋布置方式可以增强不同流道内流体的扰动,破坏热边界层,提高对流传热系数,换热性能最好;然而,由于倾斜角的存在增加了流动阻力,需要以更高的功耗为代价。综合考虑器件热阻与水泵功耗,矩形平行肋片综合性能最好。     

Equivalence analysis of accelerated degradation mechanism based on stochastic degradation models

For an effective accelerated degradation test, it is important to ensure that the degradation mechanism under different stress levels remains unchanged. In this article, we are interested in the equivalence analysis of accelerated degradation mechanism based on degradation data rather than physical or chemical techniques. Under the assumption that products' underlying degradation follows stochastic degradation models, we first introduce the relationship between mechanism equivalence and parameters of stochastic degradation models based on the acceleration factor invariant principle. Then the necessary conditions for mechanism equivalence, which should be satisfied under different stress levels, are derived and tested by the proposed parameter equivalence test method based on the modified Bartlett statistic and T statistic. Next a novel selection method for stochastic degradation models is derived therefrom by comparing the variation of coefficients of acceleration factors. The accuracy of the necessary conditions and the parameter equivalence test method is demonstrated through a simulation study. In addition, an electrical connector example with real stress relaxation data is analyzed to illustrate the proposed method further.     

An improved approach for process performance evaluation with the consideration of process yield and quality loss

In recent years, several process capability indices have received considerable research attention and increased usage in evaluating process performance and purchasing decisions in manufacturing industries. In particular, the third-generation capability index C_pmk is constructed by taking process yield and quality loss into consideration. Unfortunately, the sampling distribution of the estimated C_pmk is complicated, making the establishment of the exact confidence interval very difficult. Thus, this study applies the concept of the generalised pivotal quantity (GPQ) to derive the generalised confidence interval (GCI) for the index C_pmk. To examine the performance and the effectiveness of the GCI approach, a series of simulations is undertaken. Three types of bootstrap methods are also implemented and compared with the proposed GCI approach. The results reveal that the proposed GCI approach is superior to the three bootstrap methods since the obtained coverage rates are very close to the nominal confidence level in most of our studied cases even for small sample sizes. Therefore, this article recommends the GCI approach for evaluating process performance in real applications.