光泵亚毫米波激光器双稳自脉冲运转特性

研究了光泵亚毫米波激光器的双稳和自脉动等动力学行为.结果表明泵浦光能产生双稳效应,导致输出光的一部分定态不存在,脉动输出较易产生,脉动频率随着泵浦光强的增大而增大.     

两段式双稳半导体激光器下跳阈值点的确定

对Ｋｕｚｎｅｔｓｏｖ采用的速率方程加以修正，考虑了俄歇效应的影响，我们流子寿命不再作为常数处理，而写成载流子浓度的函数。由此导出了两段式双稳半导体激光器下跳阈值点载流子浓度所满足的隐函数解析表达式。通过该解析表达式确定出了器件存在双稳的必要条件。进而讨论了俄歇复合系数、吸收区偏置电流和长度等对双稳特性的影响。     

两段式半导体激光器的双稳条件

对Ｋｕｚｎｅｔｓｏｖ采用的速率方程加以修正，考虑了俄歇效应的影响，载流子寿命不再作为常数处理，而写成载流子浓度的函数。由此导出了两段式半导体激光器存在双稳的必要条件，计算结果表明，吸收区偏置电流对双稳条件影响极大，对具体器件而言，若增益区和吸收区隔离电阻不够大，几个ｍＡ的偏置电流泄露到吸收区就使器件难以产生双稳。     

用双稳器件做腔镜的CO_2激光器的稳态行为

近几年来,激光器的不稳定性研究引起人们的广泛兴趣。本文利用双稳器件在下态时能用做反射镜的特性,提出用双稳器件做CO_2激光器的输出腔镜。提出了该系统的物理及数学模型。稳态时,当     

长波长垂直腔面发射激光器开关及双稳特性

为了研究垂直腔面发射激光器偏振转换特性,基于自旋反转模型,数值研究了正交光注入下1550nm垂直腔面发射激光器频率诱导偏振开关及双稳特性。结果表明,在正交光注入下,连续改变注入光与激光器光场内x线性极化模的频率失谐可诱导产生两类偏振开关和偏振双稳现象,且注入光强与偏振电流的变化都显著影响双稳宽度和激光器的输出特性;合理选择操作条件,可实现对1550nm垂直腔面发射激光器频率诱导偏振开关及双稳的控制。这一结果对垂直腔面发射激光器在全光开关和全光存储等领域的应用具有参考价值。     

光泵亚毫米波激光器动力学运转状态与一般激光器的失稳行为

本文分析研究了光泵亚毫米波激光器的双稳,自脉动和混沌行为的起源,条件和范围。作为将主动腔与被动腔形式合为一体的光泵激光器系统,既具有主动腔的动力学特征,也表现出被动腔系统的行为特点。该系统的泵浦光双稳行为与双能级被动腔系统中的     

双区共腔双稳态激光器电注入下特性的计算机模拟

本文对双区共腔半导体双稳态激光器在电注入下的稳态及瞬态特性进行了计算机模拟,这种模型产生双稳和自脉动现象的机制是不均匀电注入本征可饱和吸收特性,我们研究了与可饱和吸收有关的几个参数r、ξ、J_1、J_2对双稳及自脉动现象的影响.     

H参量简化模型的调谐特性与双稳特性的关系

为了研究光栅调谐外腔半导体激光器的调谐特性和双稳特性之间的关系,采用建立H参量简化模型、以载流子密度表征阈值特性的方法,得到了以H参量表达的调谐范围解析式,对反共振所需剩余反射率的上限进行了理论分析,数值模拟了激光出射端反射系数、剩余反射率对调谐范围和双稳环环宽的影响,得到了环宽最大值的位置。结果表明,H参量简化模型能够阐明光栅调谐外腔半导体激光器的调谐特性与双稳特性的关系。     

半导体激光器光电混合双稳装置的双稳特性与器件参量之间的关系

报导了输出反馈泵浦型双稳半导体激光器双稳物性随器件参量变化的实验结果，双稳实验曲线和理论计算曲线的对比分析表明，双稳特性随各参量变化规律安全相同，实验和理论之间的微小差别来源于光探测器的实测饱和曲线和理论模型之间的差异，以及实际的半导体激光器存在自发辐射。     

集成双稳半导体激光器输出光强的线性稳定性分析

从速率方程出发,利用线性稳定性分析方法,分析了单片集成双稳半导体激光器输出光强的稳定性。结果表明此类双稳半导体激光器具有很大的双稳范围。     

PIPBQ Effect Aware SER Analysis for Combinational Logic Circuits

Technology scaling results in the propagation-induced pulse broadening and quenching (PIPBQ) effect become more noticeable. In order to effectively evaluate the soft error rate for combinational logic circuits, a soft error rate analysis approach considering the PIPBQ effect is proposed. As different original pulse propagating through logic gate cells, pulse broadening and quenching are measured by HSPICE. After that, electrical effect look-up tables (EELUTs) for logic gate cells are created to evaluate the PIPBQ effect. Sensitized paths are accurately retrieved by the proposed re-convergence aware sensitized path search algorithm. Further, by propagating pulses on these paths to simulate fault injection, the PIPBQ effect on these paths can be quantified by EELUTs. As a result, the soft error rate of circuits can be effectively computed by the proposed technique. Simulation results verify the soft error rate improvement comparing with the PIPBQ-not-aware method.     

带隙渐变纳米线的光电导淬灭效应

采用气相沉积温度梯度分布合成纳米线法,在750～950℃耐高温石英管中,在催化剂金的催化作用下,生长出310μm带隙渐变的硫硒化镉半导体纳米线,并利用倏逝波耦合的方法导波激发,分别对不同掺杂比例的部分纳米线进行研究。实验发现,在注入功率低于10-8 W时,随着光强增大不同带隙宽度的纳米线的淬灭度都在增大;然而在注入功率继续增大时,S元素比例占到90%的纳米线的淬灭度峰值最早到来,以Se元素为主的纳米线的淬灭度峰值在10-6 W注入光下仍未出现,原因是增加S元素会使更多的复合中心转变为陷阱能级中心,更多的电子可以跃迁至导带。封装上电极的带隙渐变纳米线可应用于制作高分辨率的红外光探测器,也为有效检测半导体材料的缺陷能级提供了便利。     

盖革模式雪崩光电二极管的场效应管淬灭电路设计

雪崩光电二极管（Avalanche Photondiode,APD）是一种常用于激光探测领域的光敏元件。本文针对盖革模式雪崩光电二极管（Geiger Mode-Avalanche Photondiode,Gm-APD）工作时发生的雪崩效应,设计了一种场效应管淬灭电路（Field Effect Transistor Quenching Circuit）。首先,针对Gm-APD器件的特性建立了Gm-APD的电学模型。其次,在此模型的基础上,设计并仿真验证了场效应管淬灭电路,实现了对Gm-APD的快速淬灭。结果表明,本文设计的场效应管淬灭电路淬灭速度快、死时间短、性能较优,淬灭时间和死时间分别为21.026 ns和16.5 ns,满足激光测距成像的应用需求。     

Interactions between closely coupled GaAs injection lasers

Interaction effects between injection lasers have been experimentally studied at 2°K and 77°K under pulse conditions in a single block configuration which permits close optical coupling between the lasers. This close coupling made previously reported effects an order of magnitude more prominent and revealed a new effect. The reduction of the threshold current of one laser by the influence of the coherent beam of a second laser by as much as a factor five has been observed. With respect to the quenching of one laser by a second laser, a quenching ratio (defined as the ratio of the quenched power to the quenching power) of 0.7 was obtained. A new effect observed was the reduction of the threshold current of one laser by the influence of the spontaneous emission from a second laser. A reduction of 10 per cent is typical for this effect. A qualitative discussion treating the two lasers as one optical cavity is given to incorporate these effects into one coherent picture. Logical device applications are also discussed.     

Observation of the quantum confined stark effect in ZnSe/ZnCdSe single quantum well systems

We report the observation of the quantum-confined Stark effect (QCSE) in ZnSe/ ZnCdSe single quantum wells grown by molecular beam epitaxy, using photoluminescence. In our experiments the electric field was applied via a reverse-biased Schottky barrier contact. To our knowledge, this is the first observation of the QCSE in any wide gap II-VI semiconductor heterostructure. Significant red shifts, typically 10–15 meV, are detected before quenching. An associated reduction in the transition intensity, consistent with the QCSE. is clearly observed. The dependence of these results will be discussed as a function of quantum well depth and thickness. Complete quenching of the luminescence is observed with applied voltages as low as 5 V. In addition, at lowest voltages, we also detect small blue shifts (up to 4 meV), which we attribute to the interaction between the externally applied electric field and the built-in field of the structure.     

Features of manifestation of acceptor state of gold in silicon with quenched-in donors

The effect of cyclic heat treatments and diffusion of gold into silicon with inherent quenched-in donors on the electrical properties of the material is studied. An analysis of the data on slow cooling and quenching makes it possible to conclude that the mechanisms of transformation of quenched-in donors in the course of quenching and multi-cycle heat treatment with slow cooling are different and that there are two different acceptor states of gold atoms.     

3Cr13不锈钢计数器棘轮的激光淬火研究

利用2KW横流CO_2激光器对3Cr13计数器棘轮进行了激光淬火研究,结合零件的原始加工次序,比较了两种次序激光淬火投弹器棘轮的工艺,结果表明:经两种方法激光处理后棘轮的显微硬度均达到了该零件技术指标的要求,显微硬度为HV412∽550。激光处理3Cr13不锈钢硬化层的深度为1.0mm,表面最高硬度HV680,比普通淬火高约HV160。激光处理后齿面的光洁度不变,达(Ra0.4∽0.3μm),激光淬火的变形为2.5μm左右。激光淬火区的显微组织为细小均匀的隐晶马氏体。     

红外猝灭非线性砷化镓光电导开关产生太赫兹的实验研究

在实验上对光激发电荷畴进行有效的猝灭,是利用具有雪崩倍增效应的非线性砷化镓光电导开关作为太赫兹辐射源的关键问题之一。提出了基于双光束红外激光来猝灭砷化镓光电导开关的非线性模式的初步实验方法,两束激光时延为100 ps,其中第二束为猝灭光。实验中,12 mm间隙的砷化镓光电导开关偏置电压可达到32 kV,输出电流为900 A。同时,14 mm间隙开关在20 kV偏置、毫焦光能触发条件下,可连续工作230次,输出波形具有较好的重复性。结果表明,双光束红外激光能够猝灭非线性模式,重复工作性能稳定,对高重复频率触发下光电导方法产生高功率太赫兹辐射的研究奠定了前期实验基础。     

Photoluminescence properties of solid-state Tb^3＋ doped NaY（MoO4）2

A series of Tb^3＋ doped Na Y（Mo O4）2 are synthesized by a solid-state reaction at 550 °C for 4 h, and their luminescent properties are investigated. The phase formation is carried out with X-ray powder diffraction analysis, and there is no other crystalline phase except Na Y（Mo O4）2. Na Y（Mo O4）2：Tb^3＋ can produce the green emission under 290 nm radiation excitation, and the luminescence emission peak at 545 nm corresponds to the 5D4→7F5 transition of Tb^3＋. The emission intensity of Tb^3＋ in Na Y（Mo O4）2 is enhanced with the increase of Tb^3＋ concentration, and there is no concentration quenching effect. The phenomena are proved by the decay curves of Tb^3＋. Moreover, the Commission International de I＇Eclairage（CIE） chromaticity coordinates of Na Y（Mo O4）2：Tb^3＋ locate in the green region.     

Observation of differences in the quenching of the Photocurrent in GaAs containing EL2 and EL0

The quenching of the photocurrent and photo-Hall effect of several undoped semi-insulating gallium arsenide samples has been measured and compared with the deep-level photoluminescence spectra from neighboring samples. Samples that show either EL2 (0.68 eV) or ELO (0.63 eV) photoluminescence have distinctly different photocurrent quenching behaviors. EL2 samples show a photocurrent decrease of several orders of magnitude, and a change fromn-type to p-type conduction during quenching at 80 K with 1.1 eV light. ELO samples show a reduction in photocurrent of less than an order of magnitude with no change in the carrier type at this temperature. Photo-Hall effect experiments at 80 K indicate that the conduction isn-type for the ELO samples, but changes fromn- to p-type during the quench for the EL2 samples. The temperature dependence of the quenching has also been studied. EL2 samples show little variation in the range 10-80 K, while ELO samples show significant quenching similar to EL2 after the temperature is reduced below 70 K. These results indicate that defects other than EL2 can significantly affect photocurrent quenching experiments.