垂直腔面发射激光器及其进展

1　引　　言　　光电子技术在网络、存储器等方面的应用与多媒体信息社会的发展息息相关 ,对信息社会的发展始终起着至关重要的作用。在世界范围内的信息基础设施配置中 ,人们对以光纤通信为代表的光电子技术寄予厚望。瞬间传送处理图像等大规模信息技术愈益重要 ,在并行传递空间信息的超并行光传输系统、连接多台计算机或LSI芯片的并行光互连及光并行信息处理系统中 ,新兴的并行光电子技术起主导作用。要实现充分利用光的并行性的系统 ,大规模地进行二维集成化的并行光器件十分重要。为适应这种需求 ,人们开始探索一种新型结构的半导体激…     

980 nm高功率垂直腔面发射激光器

研究了 980nm垂直腔面发射激光器 (VCSEL)的结构设计和器件制作 ,实现了室温下的脉冲激射。在脉宽为 5 0 μs,占空比为 5∶10 0 0的脉冲电流下 ,直径 4 0 0 μm的器件输出光功率最高可达 380mW ,发散角小于 10° ,光谱的半高全宽为 0 8nm。     

性能优良的光泵垂直腔面发射激光器

光泵半导体（OPS）激光器是一类以特殊类型垂直腔面发射激光器（VCSEL）为基础的新型器件，与以电流注入驱动的垂直腔面发射激光器不同，光泵垂直腔面发射激光器是用二极管泵浦激光驱动的。这种器件具有所希望的性能特性组合，如小型组件的高功率和优良TEM00模特性的组合。这种技术还可做成具有特定波长输出的激光器或在850～1600nm光谱范围可调谐的激光器。这些特性意味着光泵半导体激光器具有渗透或影响许多商业化激光应用开发的潜力，其中包括在通讯方面的应用。这方面的一个重要例子是泵浦高功率掺饵光纤放大器（EDFA）。光泵光泵…     

选择腐蚀确定垂直腔面发射激光器生长偏差对模式波长的影响

本文提出一种可在垂直腔面发射激光器外延生长后准确确定其模式生长偏差的简便方法．利用选择性湿法腐蚀，分别测出器件各主要部分的微区光反射谱，通过模拟计算得到这些部分的厚度偏差及其对模式波长偏移的影响，使调整后再生长的器件模式位置大为改善，并为器件后期制备的模式调节提供了可靠的依据     

垂直腔面发射激光器

The development and application of vertical-cavity surface-emitting lasers (VCSELs) are summarized in this paper. The emphasis is focused on the high power single and 2-D arrays bottom-emitting VCSELs with a wavelength of 980nm. A distinguished device performance is achieved. The maximum continuous-wave (CW) output power of large aperture single devices with active diameters up to 500μm is as high as 1.95W at room temperature, which is to our knowledge the highest value reported for a single device. Size dependence of the output power, the threshold current and the differential resistance are discussed. A 16 elements array with 200μm aperture size (250μm center spacing) of individual elements shows a CW output power of 1.32W at room temperature.     

光泵垂直扩展腔面发射半导体激光器的研究进展

近年来，光泵垂直扩展腔面发射半导体激光器由于其光束质量好、可实现大功率输出，受到了广泛的关注。在介绍其基本工作原理的基础上，综述了不同波段光泵垂直扩展腔面发射半导体激光器的研究现状与进展，并分析、讨论了实现高功率光泵垂直扩展腔面发射半导体激光器面临的主要问题及解决方案。     

基于AlAs氧化法研制的垂直腔面发射激光器

结合垂直腔面发射激光器的制备,研究了AlAs选择性氧化工艺中氧化炉温、氮气流量、水温等条件和AlAs层的横向氧化速率之间的关系,并得到了可精确控制氧化过程的工艺条件,在优化的工艺条件下运用湿氮氧化制备出InGaAs/GaAs垂直腔面发射激光器,实现了器件的室温脉冲激射.     

光泵浦垂直外腔面发射激光器的结构优化设计

实验中发现,传统结构的光泵浦垂直外腔面发射半导体激光器,随着泵浦功率密度的增加,器件的温升现象严重.这是由于传统结构中,势垒和量子阱间小的带隙差造成的.为了解决温升问题,采用PICS3D软件对传统结构进行优化设计.在吸收层中引入对泵浦光和激射光透明的AIGaAs层,提高对量子阱中的载流子的限制作用.计算结果表明,在增益和自发发射特性上,优化后的结构都有了很大提高.     

一种提高垂直腔面发射激光器性能的新工艺

采用一种新的工艺方法提高了垂直腔面发射激光器的输出功率.采用开环分布孔代替环形沟槽,使器件的输出功率提高了0.34倍.14μm孔径的器件输出功率超过10mW,工作电流为29.6mA时,最大输出功率达到12.48mW.而且,这些开环分布孔为电注入提供了便捷的桥通道,很好地解决了电极易过沟断线问题.器件表现了良好的高温工作特性,当温度高达60℃时输出功率仍可达到8mW.     

GaN垂直腔面发射激光器研究进展

氮化镓(GaN)垂直腔面发射激光器(VCSEL)在近20年来获得了飞速发展,已成为下一代半导体激光器的研究热点。GaN是制造从紫外波段到绿色波段光电子器件的绝佳材料,而VCSEL具有阈值和发散角小、调制速率高,以及输出光束呈圆对称等特点。首先回顾了基于GaN的VCSEL的发展历史,简要介绍了它的主要应用方向;然后讨论了反射镜与谐振腔设计与制造中的关键问题;接着分析了三种不同结构的GaN VCSEL的散热机理,并分析讨论了优化散热的策略;最后介绍了基于GaN的蓝色、绿色和紫外VCSEL的研究进展及最新思路。     

半导体激光器

Surface-emitting semiconductor lasers can make use of external cavities and optical pumping techniques to achieve a combination of high continuous-wave output power and near-diffraction-limited beam quality that is not matched by any other type of semiconductor source. The ready access to the laser mode that the external cavity provides has been exploited for applications such as intra-cavity frequency doubling and passive mode-locking.     

微透镜稳定微芯片垂直外腔面发射激光器

金刚石微透镜既可以作为输出耦合器又可以充当热沉.垂直外腔面发射激光器(VECSEL)用途广泛,制作简单,波长范围广,光束质量好,不像边发射激光器那样需要光束整形.尽管VECSEL只是平-平谐振腔集成到半导体芯片上的单片结构,但是它有单独的外部输出耦合镜.由于VECSEL的外腔输出镜的光学特性允许把聚焦或波长选择加到谐振腔的设计中,所以它比垂直腔面发射激光器(VCSEL)用途更加广泛.     

Extended Tunability in a Two-Chip VECSEL

We demonstrate a widely tunable vertical-external-cavity surface-emitting laser (VECSEL) with a W-shaped cavity, in which two VECSEL chips serve as fold mirrors and a birefringent filter is inserted at Brewster's angle. These two chips provide much higher modal gain and broader bandwidth of the gain than a single chip does, enhancing the VECSEL tuning range and reducing the variation of tunable output power with the tuned wavelength. This two-chip VECSEL configuration makes it possible to shape the modal gain spectra of the laser or to manipulate the tuning curve of the laser by two different chips with certain gain peak detuning (offset). Multiwatts high-brightness linearly polarized output with a tuning range of 33 nm is demonstrated in such a two-chip VECSEL     

光泵浦垂直外腔面发射半导体激光器的热管理

在实验基础上分析了光泵浦垂直外腔面发射半导体激光器(0PS-VECSEL)的热管理,建立了一维静态热传导方程,并结合数学工具Matlab解热传导方程,得出热沉的热导率及DBR热导率变化对器件温度的影响.实验中采用的热沉为铜热沉,用光致发光谱测量方法估算器件的温度升高.理论计算与实验结果都表明,采用铜做热沉时器件的温度升高.因此应采用热传导系数大的材料来取代铜作热沉材料,以提高器件的性能.同时表明这种简单的计算模型能为器件的设计提供有用的理论分析与指导.     

InP-based optically pumped VECSEL operating CW at 1550 nm

We present a vertical external-cavity surface-emitting laser operating at 1550 nm. The laser comprises an InGaAsP-based gain element, with a resonant periodic gain structure on top of a distributed Bragg reflector, and a high reflectivity spherical mirror as the external reflector. Optical pumping is achieved using a 1250-nm fiber Raman laser. A maximum continuous output power of 70 mW was obtained under multitransverse mode operation at 233 K. Under single-mode operation, we obtained a maximum power of 60 mW with a beam quality factor M/sup 2/ less than 1.1.     

Material research on the InGaAs-emitting-layer VECSEL grown on GaAs substrate

Wafers of InGaAs-emitting-layer vertical external cavity surface emitting semiconductor laser (VECSEL) gain chip and separate active region were grown on semi-insulator GaAs substrates by low pressure metal–organic vapor phase epitaxy (MOVPE). Photoluminescence (PL) wavelength of the active region could be adjusted linearly about 1 nm for increasing 1 sccm H₂ flow rate through TMIn under AsH₃ flow rates of 150 sccm. The complicated surface-emitted PL signal of the VECSEL gain chip was strongly modulated by interferences within the multilayer and was interpreted by the aberrance of the quantum wells emission with a profile filtered by a micro-cavity resonance in the longitudinal confinement factor. Material tests of the VECSEL wafer showed the reflectivity of the DBR mirrors was in good agreement with the active region photoluminescence, and the wafer was obtained with high crystal quality.     

4 W single-transverse mode VECSEL utilising intra-cavity diamond heat spreader

An optically pumped semiconductor vertical external cavity surface emitting laser, with high output power and excellent beam quality operating at a wavelength near 1.05 /spl mu/m, is reported. A transparent diamond heat spreader was used for thermal management of the laser. The gain structure grown by molecular beam epitaxy includes 13 compressively strained InGaAs quantum wells. Maximum output power of 4 W with diffraction-limited beam (M/sup 2//spl les/1.15) was achieved using a 2% output coupler and incident pump power of 20 W. It is shown that power scalability is feasible with the presented laser geometry.     

EQUAL INTERVAL RANGE APPROXIMATION AND EXPANDING LEARNING RULE FOR MULTI-LAYER PERCEPTRONS AND APPLICATIONS

In this paper,we propose an equal interval range approximation and expandinglearning rule for multi-layer perceptrons applied in pattern recognitions.Compared with tra-ditional BP algorithm,this learning rule requires the output activations interval between themaximum target output node and other nodes to exceed a given equal interval range for eachtraining input pattern,thus it can train networks faster in much lower calculation cost andmay avoid the occurrences ot reversed target output and overlearning,hence it can improve thenetwork's generalization abilities in pattern recognitions.Through gradually expanding of theinterval range,this learning rule can also enable the network to learn its targets more accuratelyin less additional training iterations.Finally,we apply this algorithm in network training inEEG detection,and the experimental results have shown the above advantages of the proposedalgorithm.     

一种SAR压制干扰区域扩展的方法改进

在分析正弦调频干扰和方位向间歇采样转发干扰信号的干扰原理和干扰效果的基础上,发现正弦调频在二维干扰的情况下能产生大面积多虚假目标,达到有效的对真实目标进行压制式遮盖;方位向间歇采样可以在方位向产生多点虚假目标。通过有效地结合两种干扰方法的优点,达到可沿方位向有效扩展干扰范围的效果。最后,利用仿真实验验证了理论的正确性。