径向桥电极高功率垂直腔面发射激光器

为改善高功率垂直腔面发射半导体激光器的热特性,提高它的输出功率,研制了新型径向桥电极高功率垂直腔面发射半导体激光器器件,对新型半导体激光器的结构模型进行理论分析表明,采用径向桥式电极可以降低器件P型DBR电阻,减小焦耳热;降低热阻,提高器件的散热能力。实验制备了出光孔径同为200μm的径向桥电极与常规电极的高功率垂直腔面发射半导体激光器,并对器件的性能进行了实验对比测试。结果表明径向桥电极高功率垂直腔面发射半导体激光器器件的微分电阻为0.43Ω;室温下最大输出功率可达340 mW,是常规电极垂直腔面发射半导体激光器的1.7倍;器件的热阻为0.095℃/mW,在80℃时,仍能正常激射,具有良好的热特性,径向桥电极高功率垂直腔面发射半导体激光器的光电特性与温度特性要远好于常规电极的高功率垂直腔面发射半导体激光器器件。     

增益导波垂直腔激光器注入电流空间分布及其对激光近场模式影响的理论分析和表征

依据导电介质的稳态电场理论建立了一种对增益导波型垂直腔半导体激光器注入电流矢量分析的三维解析模型. 计算研究了电流密度空间分布及其与顶面电注入环参量之间的相互关联性. 结果显示在两极之间存在一个载流子径向分布中心极大的区域. 由于激光功率与注入电流之间存在线性关系,因此,要使器件能够获得基模或中心均匀的光强输出以及尽可能低的阈值,应使激光有源层与载流子均匀分布的临界层重合. 计算结果对顶发射与底发射结构以及不同环参数下的载流子分布情况及对近场模式形成的影响进行了分析和讨论. 关键词： 垂直谐振腔激光器 注入电流 激光模式     

利用光学薄膜模型研究垂直腔面发射激光器的光学特性

可以把垂直腔面发射激光器看作是多层光学薄膜,应用光学薄膜原理对其光学薄膜的特性进行了研究。计算分析了布拉格反射镜和谐振腔模的反射谱受器件结构变化的影响。通过利用菲涅耳系数矩阵法计算,得到了光在垂直腔面发射激光器器件结构中形成的驻波场分布。结果表明,利用菲涅耳系数矩阵法设计垂直腔面发射激光器的光学薄膜是一种快捷准确的方法。     

AlInGaAs/AlGaAs垂直腔面发射激光器温度特性的对比研究

通过测量、对比材料生长和器件制备条件基本相似，但是谐振腔腔模波长与增益峰值波长相对位置明显不同的两类氧化物限制型应变AlInGaAs/AlGaAs量子阱垂直腔面发射激光器(VCSEL)在261—369K温度范围内输出光功率-电流的变温曲线，同时结合测试得到的两类样品的白光反射谱、光荧光谱以及模拟计算得到的不同温度下VCSEL反射谱和增益谱，分析了输出光功率、阈值电流、斜率效率和激射波长随温度变化的关系，掌握了新材料AlInGaAs的温度特性，得到了谐振腔腔模波长和增益峰值波长的相对位置对VCSEL输出特性，尤其是对阈值的影响规律，指出获得室温工作阈值最低且稳定的VCSEL的一个方法是调整谐振腔腔模波长和增益峰值波长的相对位置，并利用这种方法获得了特征温度T₀=333K的AlInGaAs/AlGaAs量子阱VCSEL器件. 关键词： AlInGaAs 垂直腔面发射激光器 特征温度     

高功率垂直腔面发射半导体激光器优化设计研究

与传统的端发射半导体激光器相比，垂直腔面发射半导体激光器（VCSEL）具有可单模输出，光束对称性好，可被高度聚焦，进入光纤的耦合效率极高和有利于大规模二维列阵等优 点.为了得到高功率的激光输出，除了要增大VCSEL的发射面积之外，关键的是要选择适 当的量子阱层数、有源区电流密度的均匀分布和良好的热管理等.本文详细研究和分析了高功率VCSEL有源区量子阱层数，有源区直径，材料的热导和电阻，电极间距等对VCSEL 器件性能的影响.通过优化参数，进行最佳设计，研制出了980 nm In0.2Ga0.8As/Ga 关键词： 垂直腔面发射激光器（VCSEL） 量子阱 高功率     

面向系统仿真的垂直腔表面发射半导体激光器模型

建立了一个基于速率方程,考虑了热效应、空间烧孔效应的垂直腔表面发射半导体激光器的模型,并根据其物理和几何特性,通过正交变换简化了速率方程的计算,从而得到一个新的高效的面向系统连接的仿真模型,并将此模型用于激光器和光纤之间的耦合。实验结果表明,此模型可以广泛地应用于面向系统连接的光学仿真。     

用速率方程分析垂直腔面发射激光器的噪声

采用一种合理的噪声模拟方法，用速率方程对垂直腔面发射激光器的噪声特性进行了数值分析，在单模情况下计算了器件的自发辐射因子、输出功率、注入电流、阈值电流等参数与相对强度噪声、频率噪声以及线宽等特性的关系，计算结果与实验基本相符，对优化垂直腔面发射激光器的结构设计和应用条件有所裨益. 关键词：     

垂直腔面发射半导体微腔激光器

评述了垂直腔面发射半导体激光器研究的最新进展,就其结构特点、应变量子阱结构、超晶格镜面和微腔效应作了简要的论述,探讨了进一步降低半导体激光器阈值的途径,介绍了新型的氧化约束型垂直腔面发射半导体激光器,并对微腔激光器中自发辐射增强效应和三维封闭腔的特性给出了描述,同时展望了该器件的应用及发展前景。     

n型DBR中电势对垂直腔面发射激光器阈值的影响

编制了增益波导垂直腔面发射激光器直接耦合准三维仿真软件，给出了电势、 载流子浓度、光场和热场分布.计算结果表明，只有同时考虑p型和n型分布布拉格反射镜中的电势，才能准确地反映垂直腔面发射激光器的阈值特性. 关键词： 垂直腔面发射激光器 p型DBR层 n型DBR层 有限差分法     

微热通道电极结构宽条形半导体激光器输出特性

为了抑制宽条形半导体激光器的热透镜效应,提高慢轴光束质量,本文提出并制作了一种微热通道电极结构激光器.该芯片p面注入区电极处被设计为较厚的高热导率的电极结构,封装后激光器两侧与热沉之间形成空气间隙,抑制激光器有源区横向热流,使激光器内温度分布均匀,有效地降低慢轴发散角.对该激光器的封装模型进行了稳态热分析,优化了微热通...     

Graded index profiles and loss-induced single-mode characteristics in vertical-cavity surface-emitting lasers with petal-shape holey structure

The 850-nm oxide-confined vertical-cavity surface-emitting lasers with petal-shape holey structures are presented.An area-weighted average refractive index model is given to analyse their effective index profiles,and the graded index distribution in the holey region is demonstrated.The index step between the optical aperture and the holey region is obtained which is related merely to the etching depth.Four types of holey vertical-cavity surface-emitting lasers with different parameters are fabricated as well as the conventional oxide-confined vertical-cavity surface-emitting laser.Compared with the conventional oxide-confined vertical-cavity surface-emitting laser without etched holes,the holey vertical-cavity surface-emitting laser possesses an improved beam quality due to its graded index distribution,but has a lower output power,higher threshold current and lower slope efficiency.With the hole number increased,the holey vertical-cavity surface-emitting laser can realize the single-mode operation throughout the entire current range,and reduces the beam divergence further.The loss mechanism is used to explain the single-mode characteristic,and the reduced beam divergence is attributed to the shallow etching.High coupling efficiency of 86% to a multi-mode fibre is achieved for the single-mode device in the experiment.     

On the thermal resistance of vertical-cavity surface-emitting lasers

Thermal properties of vertical-cavity surface-emitting lasers (VCSELs) are studied using their comprehensive, three-dimensional, self-consistent, thermal-electrical simulation. The thermal resistance versus operation current relation is found to be completely different for two basic VCSEL configurations, i.e. for proton-implanted top-surface-emitting lasers (top-emitting VCSELs) and etched-well lasers (bottom-emitting VCSELs). The above fact is explained using a concept of the average centre of heat generation within a laser volume and its shift with an increase in an operation current. This revised version was published online in November 2006 with corrections to the Cover Date.     

Enhanced thermal stability of VCSEL array by thermoelectric analysis-based optimization of mesas distribution

The thermal stability of a vertical-cavity surface-emitting laser(VCSEL) array is enhanced by redesigning the mesa arrangement. Based on a thermoelectric coupling three-dimensional(3D) finite-element model, an optimized VCSEL array is designed. The effects of this optimization are studied experimentally. Power density characteristics of VCSEL arrays with different mesa configuration are obtained under different thermal stress in which the optimized device shows improved performance. Optimized device also shows better stability from measured spectra and calculated thermal resistances. The experimental results prove that our simulation model and optimization is instructive for VCSEL array design.     

Analytical modelling of end thermal coupling in a solid-state laser longitudinally bonded by a vertical-cavity top-emitting laser diode

The intrinsic features involving a circularly symmetric beam profile with low divergence, planar geometry as well as the increasingly enhanced power of vertical-cavity surface-emitting lasers (VCSELs) have made the VCSEL a promising pump source in direct end bonding to a solid-state laser medium to form the minimized, on-wafer integrated laser system. This scheme will generate a surface contact pump configuration and thus additional end thermal coupling to the laser medium through the joint interface of both materials, apart from pump beam heating. This paper analytically models temperature distributions in both VCSEL and the laser medium from the end thermal coupling regarding surface contact pump configuration using a top-emitting VCSEL as the pump source for the first time. The analytical solutions are derived by introducing relative temperature and mean temperature expressions. The results show that the end contact heating by the VCSEL could lead to considerable temperature variations associated with thermal phase shift and thermal lensing in the laser medium. However, if the central temperature of the interface is increased by less than 20~K, the end contact heating does not have a significant thermal influence on the laser medium. In this case, the thermal effect should be dominated by pump beam heating. This work provides useful analytical results for further analysis of hybrid thermal effects on those lasers pumped by a direct VCSEL bond.     

High-power vertical-cavity surface-emitting lasers bonded with efficient packaging

<正>High-power vertical-cavity surface-emitting lasers(VCSELs) are processed using a wet thermal-selective oxidation technique.The VCSEL chips are packaged by employing three different bonding methods of silver solder,In-Sn solder,and metalized diamond heat spreader.After packaging,optical output power, wavelength shift,and thermal resistance of the devices are measured and compared in an experiment.The device packaged with a metalized diamond heat spreader shows the best operation characteristics among the three methods.The 200-μm-diameter device bonded with a metalized diamond heat spreader produces a continuous wave optical output power of 0.51 W and a corresponding power density of 1.6 kW/cm~2 at room temperature.The thermal resistance is as low as 10 K/W.The accelerated aging test is also carried out at high temperature under constant current mode.The device operates for more than 1000 h at 70℃,and the total degradation is only about 10%.     

Optical simulation of vertical-cavity surface-emitting lasers with non-cylindrical oxide confinement

Two extensions of weighted index method are presented in order to calculate the splitting of degeneracy for non-circular vertical-cavity surface-emitting lasers. Both of them automatically satisfy which transverse optical modes split, and give a reliable approximation for the resonant frequencies, threshold gains and confinement factors. The intuitive effective radius method traces back the splitting for different effective aperture radii which are defined according to the transverse intensity distributions. The hybrid analytical axial and numerical lateral method is more precise from a mathematical point of view, and provides the mode patterns as well as the optical data.     

Control of gain and thermal carrier loss profiles for mode optimization in 980-nm broad-area vertical-cavity surface-emitting lasers

Optical gain and thermal carrier loss distributions regarding current diffusion and various electric contact areas are investigated to improve the near-field modes from the ring-shape to a Gaussian-like configuration for extra-broad-area and oxide-confined vertical-cavity surface-emitting lasers. In this work an equivalent circuit network model is used. The resistance of the continuously-graded distributed Bragg reflectors （DBRs）, the current diffusion and the temperature effect due to different electric-contact areas are calculated and analyzed at first, as these parameters affect one another and are the key factors in determining the gain and thermal carrier loss. Finally, the gain and thermal carrier loss distributions are calculated and discussed.     

Suppression of polarization switching in vertical-cavity surface-emitting lasers by use of optical feedback

The polarization properties of vertical-cavity surface-emitting lasers (VCSELs) subject to optical feedback are studied experimentally. It is thereby demonstrated that polarization-selective optical feedback can be utilized to entirely eliminate VCSEL polarization switching over the entire device operating range.