注入式激光器的自动偏置控制

本文叙述使用纯电子学线路稳定注入式激光器的一种新方法。这种方法用电路来监视激光器的电压和电流,并自动调整激光器偏置,使得在由交流信号调制激光器电流时,激光器     

冲击电流驱动下半导体激光器的快速响应研究

基于半导体激光器的单模速率方程,采用典型参数对其进行建模仿真,仿真结果表明:半导体激光器在初期的光子受激辐射速率随着注入电流的增大而增加,上升时间随着注入电流的增大而减少。但对于固定功率限制范围的半导体激光器,不能通过直接增大注入电流来减少上升时间,考虑到半导体激光器的发热问题,提出了一种在正常脉冲发光电流前端加入冲击电流来减少半导体激光器发射脉冲上升时间的方法,保证了半导体激光器的稳定输出。通过仿真对该方法进行验证,并对型号为PLTB450B半导体激光器进行了测试。仿真结果与测试结果均表明:通过加入冲击电流的方法,可以大大减少固定功率的半导体激光器发射脉冲的上升时间。     

基于AD7888的高稳定度激光器多路监测系统的设计

在高稳定度激光器的研制中,实时监测激光器的工作状态是需要重点关注的问题。本系统实现了高稳定度激光器温度控制系统、激光管工作电流、工作电压、激光器光功率的实时精确监测,以及激光器工作状态数据的存储和数据串行上传的功能。其中电流设定值和实际工作电流的观测可以更好地确定激光器的工作状态。系统结构图如图1所示。     

150mW光输出的半导体激光器

三洋制造的150mW 光输出半导体激光器,输出波长为800～870nm,室温连续使用寿命5000小时,它的发光层与电流通过区段之间具有减少光吸收达到高功率输出和高可靠工作的最佳间隙,其振荡保持单纯横向模状态。激光器刻面有一电流阻塞区,用以降低电流引起的温度上升,减少光吸收,防止激光器刻面的光学损坏。该激光器振荡起始电流170mA,     

分布反馈激光器温度与电流控制研究

为了精密控制分布反馈激光器的温度与电流, 采用数字信号处理芯片, 设计了分布反馈激光器驱动装置。通过该装置设定激光器温度和电流的参考电压, 经数模转换, 再通过温度和电流驱动模块, 馈入并驱动分布反馈激光器, 进行了实验验证。结果表明, 40min内温度变化极差与标准差分别不超过5mK和0.7mK, 电流变化极差与标准差不超过40μA和6μA; 驱动半导体光放大器, 关断时间小于1μs, 具有良好的瞬间响应特性; 该装置具有较高的温度和电流稳定性, 流控模块具有良好的瞬态特性, 能够精密控制分布反馈激光器的温度和电流。该控制装置可用于光腔衰荡光谱研究, 控制分布反馈激光器并驱动光放大器来关断激光。     

量子点激光器瞬态响应及调制特性分析

基于二能级系统建立量子点激光器的载流子-光子速率方程模型,分析量子点激光器的瞬态响应和调制特性,获得其动态特性.同时分析了注入电流对量子点激光器输出光子密度的影响,随着注入电流的增大,激光器光电延迟时间缩短,弛豫过程缩短,弛豫振荡频率增大,且输出光子峰值和稳态功率增加,适当增加注入电流可拓宽量子点激光器调制带宽.通过小信号调制分析,发现量子点激光器上限调制频率比普通激光器高一个数量级,证明了其具有良好的高频调制特性.     

5000小时室温连续激射GaAs/GaAlAs双异质结激光器

简述了所研制的质子轰击条形双异质结激光器的结构和工艺。在直流正向电流下对激光器性能进行了测试分析,大部分激光器的阈电流I为50～150毫安,微分量子效率η_d为30～70％,部分激光器得     

双频微片激光器的功率均衡机制实验研究

为了研究双频Nd:YVO₄微片激光器的功率均衡机制,利用实验研究分析了微片激光器的抽运电流、工作温度和谐振波长等参量之间关系。不断增大双频激光器抽运电流,通过降低晶体温度不断重新实现双频激光功率的均衡,最终获得了不同抽运电流下的双频激光器的功率均衡温度,以及双频功率积与抽运电流的关系数据。结果表明,双频激光信号功率均衡温度与抽运电流呈分段负相关,双频功率积与抽运电流呈正相关。此结果说明通过改变抽运电流和温控温度可以实现功率可调的功率均衡的双频激光信号输出。     

镇流电阻对He-Ne激光器稳定性影响

He-Ne激光器是最常用的一种激光器,He-Ne激光器中的放电是放电电流比较小、放电电压比较     

低偏置电流下大功率半导体激光器低频电噪声特性

测量了大功率InGaAsP/GaAs量子阱半导体激光器在五十分之一阈值电流下的电压低频噪声功率谱密度.实验结果显示,激光器的低频电噪声呈现1/f噪声,在不同的偏置电流范围内,1/f噪声幅度随电流的变化关系不同,整体上随偏置电流的增大而减小,实验中并未发现g-r噪声.结合低偏置电流时激光器动态电阻的大小,给出了1/f噪声的模型,分析了在低偏置电流下的1/f噪声主要来自有源区和漏电电阻,其幅度的大小及其随偏置电流的变化趋势与激光器的可靠性有密切的关系.     

导电聚苯胺在太赫兹波段的光电性能研究

导电聚苯胺是一种掺杂高分子半导体,内部含有大量的自由载流子,同时含有大量被束缚的载流子。本文利用太赫兹时域光谱装置测量了不同电导率的聚苯胺在0.3～2.8 THz的光谱特性,得到了其在太赫兹波段的吸收系数、折射率和介电常数等光电参数。研究了电导率对其吸收系数、折射率和介电常数的影响,对半导体材料中载流子与太赫兹波的相互作用的研究具有重要意义。     

Pulsed laser annealing of single-crystal and ion-implanted semiconductors

The dynamic characteristics of both single-crystal and ion-implanted semiconductor layers annealed by a pulsed high-power laser beam is examined analytically for the first time by means of a parametrized perturbation method. The laser-induced lattice temperature rise is explicitly related to the laser beam parameters as well as the semiconductor properties. Specifically, the temperature in the annealed semiconductor is characterized in terms of the ambipolar diffusion length of hot, excess charge carriers, the optical attenuation coefficient of the medium, and the operating laser power, and the threshold pulse energy for surface melting is calculated for the case of silicon devices. It is shown that the pulse energy required for the onset of surface melting is sensitively dependent on the optical absorption coefficient, decreases significantly with increasing pulse intensity, and increases remarkably with increasing diffusion length of excess charge carriers.     

窄线宽半导体激光器件

分布反馈半导体激光器的线宽一般较大，难以满足光纤传感等领域的要求。根据C.H. Henry于1982年提出的半导体激光器的线宽理论，通过适当设计DFB半导体激光器的腔长、耦合系数、微分增益、光限制因子，能有效地减小激光器的线宽。同时，空间烧孔现象也可限制DFB半导体激光器的线宽，为此需要合理设计光栅结构。在此基础上，DFB激光器的线宽能达到几十千赫兹的量级。此外，采用DBR结构或者外腔结构，也可以获得相当窄的线宽。     

单量子阱半导体激光器在输出反馈损耗调制方式下的双稳特性

利用速率方程求出了输出反馈损耗调制型双稳半导体激光器输出光强稳态解的解析表达式。利用双区共腔ＧａＡｓ／ＡｌＧａＡｓ单量子阱半导体激光器，观测到半导体激光器在输出反馈损耗调制方式下的光双稳特性。比较速率方程解的理论计算曲线和实验观测到的双稳特性曲线后发现，两种双稳特性曲线随反馈损耗调制系数等器件参量变化的规律完全一致。     

Spectral properties of angled-grating high-power semiconductorlasers

We study the spectral properties of angled-grating high-power semiconductor lasers, also known as α distributed feedback (DFB) lasers. We have derived a closedform expression to describe the cavity resonance. The results of this model are shown to compare favorably with experimental data. Intrinsic device parameters such as coupling coefficient and grating period are shown to be correlated to spectral and nearfield characteristics. The formulations and insights developed in this paper allow one to calculate these critical design parameters for optimum performance     

Reliability of diagnostic methods based on low-frequency noise analysis

Various methods for separating an integrated circuit (IC) batch were considered using noise parameters for the purpose of determining their reliability. The existing methods for screening semiconductor products using low-frequency (LF) noise were tested on transistors, as well as both digital and analog ICs, and showed good results. Selection criteria for semiconductor products were determined based on the statistics of a representative sample; however, their reliability was not estimated. The calculation of the correlation coefficient of determined LF noise parameters and reference reliability testing results was taken as the basis of the determination of reliability of diagnostic methods. For the experiment, KR142EN5A ICs made by bipolar technology were selected, which represent three-pin stabilizers with a fixed output voltage from 5 V and are used in many radio-electronic devices.     

耦合半导体制冷系统性能特性的优化分析

以制冷系数和制冷率为目标函数 ,探讨耦合半导体制冷系统的性能特性 ,导出最大的制冷系数和制冷率 ,优化半导体制冷器的内部结构 ,确定工作电流的最佳范围 .所得结果可为耦合半导体制冷系统的优化设计和最佳运行提供一些有价值的理论依据     

Nonlinear analysis of nano-cluster doped fiber

Superhigh speed and broad band communication system is a mainly research direction in future. The systems such as optical switch, wavelength conversion amplifier, super short pulse trains[1] laser and other new optical components are based on fiber nonlinear effect[1,2]. At the same time nano- material is one of the most influencing study field in the world. Integrating nano-technology with fiber technology, we can get the new type fiber which is fiber adulterated with nano- cluster. When the …     

Estimation of the thermal band gap of a semiconductor from seebeck measurements

It is shown that the magnitude of the Seebeck coefficient of a semiconductor has a maximum value that is close to one-half the energy gap divided by eT. An expression for the position of the Fermi level at which the Seebeck coefficient has a maximum or minimum value is derived, with account taken of the mobility and effective mass ratios. It is concluded that measurement of the Seebeck coefficient as a function of temperature on any novel semiconductor is one of the simplest ways of estimating its band gap.     

Wavelength chirp and dependence of carrier temperature on currentin MQW InGaAsP-InP lasers

In this paper, we derive a relation between the wavelength chirp and carrier temperature in semiconductor lasers. The coefficient relating the change in carrier temperature and chirp is expressed in terms of the temperature derivative of the optical gain, and two parameters describing the variation of refractive index produced by the variation of optical gain due to change of carrier quasi-Fermi level separation or carrier temperature. We have measured these parameters for MQW InGaAsP lasers, Using this data, we estimated the rate of the temperature increase with current above threshold in these devices, which is 0.13 K/mA