InGaAsP/GaAs单量子阱半导体激光器光学特性的研究

用改进的液相外延方法 L PE 生长了无铝的 In Ga As P/Ga As分别限制单量子阱半导体激光器 ,测量其远场分布近似为高斯分布 .用缓变波导理论分析了产生这种分布所对应的光波导结构的折射率分布模型 ,并简单解释了其生成原因 ,为改善光束质量提供了参考     

小发散角量子阱激光器研究

使用三层平板波导理论分析了半导体量子阱激光器远场分布。针对大功率激光器讨论了极窄和模式扩展波导结构方法减小垂直方向远场发散角,得到了极窄波导结构量子阱激光器远场分布的简化模型,获得了垂直发散角的理论值,垂直方向远场发散角减小为28.6°;使用传输矩阵方法模拟了模式扩展波导结构量子阱激光器的近场光斑及远场分布,垂直方向远场发散角减小为16°。实验测试了极窄和模式扩展波导结构量子阱激光器的垂直发散角,理论结果与实验测试获得的发散角基本一致,实现了降低发散角的要求,获得了小发散角量子阱激光器。     

具有GRIN—SCH量子阱结构激光器光波导及光场特性分析

本文给出了具有ＧＲＩＮ－ＳＣＨ结构量子阱激光器的光波导模型和详细的数值计算方法,并计算分析了ＡｌｘＧａ１－ｘＡｓＧＲＩＮ层中Ａｌ浓度和ＧＲＩＮ层厚度对等效折射率的影响,给出了ＧＲＩＮ层厚的最佳值范围;给出了宽接触ＩｎＧａＡｓ／ＡｌＧａＡｓＧＲＩＮ－ＳＣＨ量子阱激光器的近场分布三维图形,并由近场分布通过快速傅里叶变换求出了远场分布。计算得到的近、远场分布图形与实际器件测试得到的结果相符合。     

多量子阱波导场的等效折射率近似分析

当多量子阱周期与芯区厚度之比趋于零时,利用转移矩阵技术,证明了任意折射率分布多量子阱波导的场分布与其等效折射率波导的场分布近似相等,为利用等效折射率方法分析多量子阱波导特性充实了理论基础,文中的数值实例表明了理论的正确性。     

折射率线性分布多量子阱波导的色散特性

本文根据标量Ｈｅｌｍｈｏｌｔｚ方程，采用转移矩阵技术，严格求出了折射率线性分布多量子阱波导芯子区域的精确色散关系，并由Ｆｌｏｑｕｅｔ理理论进一步获得了等效折射率公式与近似色散方程，数值计算结果显示出该波导的色散特性以及与波导结构的关系，发现该量子阱波导的双折射性质与入射波长有关。     

折射率线性分布多量子阱波导的色散特性

本文根据标量Ｈｅｌｍｈｏｌｔｚ方程，采用转移矩阵技术，严格求出了折射率线性分布多量子阱波导芯子区域的精确色散关系，并由Ｆｌｏｑｕｅｔ理论进一步获得了等效折射率公式与近似色散方程，数值计算结果显示出该波导的色散特性以及与波导结构的关系，发现该量子阱波导的双折射性质与入射波长有关。     

用MOCVD制作极窄的改进型单量子阱激光器

研究者们采用金属有机化学汽相淀积(MOCVD)工艺制成了低阈值和高微分量子效率的单量子阱和多量子阱激光器。不久前,用分子束外延法已制成极低阈值电流密度的改进型多量子阱激光器。一种更基本的结构-单量子阱激光器,由于结构简单和内界面数较少,也令人感兴趣。然而,现有资料表明,除了很好简并掺杂和在低温(77K)下使用外,一般单量子阱激光器的阱宽小于80(?)时就不能工作。最近,报导过一种梯度折射率波导单独限制异质结激光器。我们采用这种结构制成了极窄单量子     

半导体量子阱激光器计算机辅助分析

介绍了一种基于Visual C 的量子阱激光器计算机辅助分析工具，采用分层迭代逼近法，提供了单量子阱激光器的计算模型。可以对突变折射率波导进行模式分析，也可以对任意折射率分布的渐变折射率波导进行精确分析。     

InGaAs／AlGaAs单量子阱激光器低阈值激射

研制了InGaAs/AlGaAs SQW激光器,对其工作特性如阈值电流密度、激射波长、特征温度、远场分布等进行了研究. 用MOCVD方法生长制备了InGaAs/AlGaAs分别限制单量子阱结构材料,得出其各层组分和能带分布.首先在GaAs衬底上生长GaAs缓冲层和AlGaAs波导层,然后生长窄能带的AlGaAs量子阱势垒层,再继续生长InGaAs量子阱有源区.其后继续生长AlGaAs势垒层、高Al组分AlGaAs波导层和GaAs高掺杂欧姆接触层.我们发现在低温范围里(160 K～220 K)阈值电流密度随温度升高而减小,与普通量子阱激光器正相反,表现出负的特征温度.随着温度进一步提高,阈值电流密度表现出指数式增大.300 K下腔长2000 μm的激光器最低的阈值电流密度约为200 A/cm2.(OD7)     

对称非线性包层平板多量子阱波导TE模的传播特性

分别用精确计算和方均近似方法得到了包层及衬底均为非线性Ｋｅｒｒ型介质、芯区为多量子阱的对称平板波导中ＴＥ模的传播特性。数值计算表明,当芯区多量子阱的层数较多时,方均根近似方法得到的结果与用精确方法得到的结果一致。此时多量子阱波导可以等效为均匀介质。对于自聚焦情况,在合适的光功率下,当分界面处包层（及衬底）的有效折射率与芯区折射率相等时,芯区的场分布呈无效分布而两侧的均呈指数式衰减;功率继续增大时,     

Performance of Hybrid Laser Diodes Consisting of Silicon Slab and InP/InGaAsP Deep‐Ridge Waveguides

The fundamental transverse mode lasing of a hybrid laser diode is a prerequisite for efficient coupling to a single‐mode silicon waveguide, which is necessary for a wavelength‐division multiplexing silicon interconnection. We investigate the lasing mode profile for a hybrid laser diode consisting of silicon slab and InP/InGaAsP deep ridge waveguides. When the thickness of the top silicon is 220 nm, the fundamental transverse mode is lasing in spite of the wide waveguide width of 3.7µm. The threshold current is 40 mA, and the maximum output power is 5 mW under CW current operation. In the case of a thick top silicon layer (1 µm), the higher modes are lasing. There is no significant difference in the thermal resistance of the two devices.     

Very low threshold GRIN-SCH GaAs/GaAlAs laser structure grown by OM-VPE

In a recent publication we gave preliminary results on the lasing characteristics of a GRIN-SCH GaAs/GaAlAs laser grown by OM-VPE. The parameters of this single quantum well laser have now been further optimised, and for a quantum well thickness of 60 ?, with outer confinement layers composed of Ga0.4Al0.6As, significantly lower threshold current densities have been achieved. For a broad-area laser of cavity length 413 ?m (width 140 ?m) the average threshold current density is 232 A cm?2, and this decreases to 121 A cm?2 for a chip length of 1788 ?m. We believe that these are the lowest lasing threshold current densities that have yet been reported.     

色散平坦渐减光纤中自相似脉冲演化特性研究

从脉冲在光纤中传输所满足的非线性薛定谔方程出发,采用分布傅里叶方法对脉冲在色散平坦渐减光纤中自相似脉冲演化特性进行了研究。结果表明：双曲正割脉冲在不同初始能量和初始脉冲宽度的情况下,色散平坦渐减光纤可以产生带有线性啁啾的自相似脉冲。进一步研究表明,随着初始啁啾增加,脉冲逐渐展宽且展宽速度逐渐加快,而演化特性的劣化程度随啁啾参量的增加而增大;当初始啁啾为正时自相似脉冲演化特性劣于负啁啾时的特性。     

LD条宽对激射波长影响的研究

报道了LD激射波长会随条宽发生明显变化.对有相同外延生长结构和制作工艺、不同条宽的960 nm LD的激射波长进行研究发现,条宽为130、100、75和50 μm的器件的激射波长依次变短.进一步分析认为,这是因为条宽变窄导致器件阈值电流密度、阈值载流子密度变大造成的.根据GaAs材料在不同注入载流子密度下的增益谱及器件条宽变化对阈值载流子密度的影响,可以对实验现象进行合理的解释,从而在器件研制中可通过改变条宽对器件的激射波长在一定范围内进行调节.     

Optical gain in GaAs/GaAlAs graded-index separate-confinementsingle-quantum-well heterostructures

Optical model gain in both the TE and TM polarizations of graded-index separate-confinement single-quantum-well heterostructure lasers measured at various levels of injection current on samples with different quantum-well widths is discussed. Lasers with wide quantum wells (⩾120 Å) have emission and gain spectra which exhibit two peaks, caused by the n=1 and n=2 subband transitions. With ordinary cavity parameters, the saturation gain of the n=1 subband transitions is lower than the cavity loss of the laser, and the lasers always lase at the n=2 transitions. Reducing the quantum-well width increases the saturation gain of the n=1 transitions enough to allow lasing from them, even in cases of higher cavity loss. Further, for a fixed cavity loss, reduction of the quantum-well width decreases the threshold current density for n =1 lasing transitions, while that for n=2 lasing increases. The superlinear increase of the material gain with the decrease of the well width reduces the minimum cavity length for n =1 subband lasing. Narrower quantum wells with higher mirror reflectivity allow shorter cavity lengths while retaining n=1 lasing, resulting in low threshold current     

基于双缝干涉水导激光打孔的仿真研究

水导激光加工技术具有热效应小、精度高、无刀具损坏等优点,被应用到高精度元件的加工中。为减小激光聚焦光斑直径以利于激光与水射流的精确耦合、提高激光孔的质量,提出了基于双缝干涉原理以减小激光聚焦光斑直径的方法。构建了传统水导激光和双缝干涉水导激光打孔的几何模型和数学模型;基于COMSOL分别进行仿真,对比和分析了在激光束参数、加工条件均相同的条件下,传统水导激光和双缝干涉水导激光打孔时对激光孔轮廓的演化、热影响区域分布和重铸层大小的影响。结果表明:与传统水导激光相比,采用双缝干涉水导激光加工技术能有效地减小激光孔直径、锥角、热影响区域宽度和重铸层大小,在现有条件下进一步减小激光聚焦光斑直径。     

Threshold voltage model for small geometry AlGaN/GaN HEMTs based on analytical solution of 3-D Poisson's equation

A simple and accurate analytical model for the threshold voltage of AlGaN/GaN high electron mobility transistor (HEMT) is developed by solving three-dimensional (3-D) Poisson equation to investigate the short channel effects (SCEs) and the narrow width effects present simultaneously in a small geometry device. It has been demonstrated that the proposed model correctly predicts the potential and electric field distribution along the channel. In the proposed model, the effect of important parameters such as the thickness of the barrier layer and its doping on the threshold voltage has also been included. The model is, further, extended to find an expression for the threshold voltage in the sub-micrometer regime. The accuracy of the proposed analytical model is verified by comparing the model results with 3-D device simulations for different gate lengths and widths.     

Ag纳米颗粒有机薄膜受激辐射增强研究

为进一步降低有机半导体材料的激射阈值,文章研究利用银纳米颗粒的表面等离子体共振效应来实现对有机半导体薄膜受激辐射的增强.将制备好的Ag纳米溶液旋涂于玻璃基底上,然后在其上再旋涂PS:Alq3:DCJTB有机薄膜发光层,构成平面波导结构.用355nm波长的YAG激光泵浦样品.实验发现:相比于无Ag纳米颗粒情况,有Ag纳米...     

Performance of optical cable composed of dispersion-shifted single-mode fibers

A low-loss dispersion-shifted single-mode fiber cable has been fabricated. The index-profile of the fiber is nearly parabolic and the relative index difference is 0.8 percent. An average cable loss is 0.229 dB/km at 1.55 μm, and excellent loss stability has been achieved in the cabling process and in the temperature and mechanical test.     

塑料激光介质的激光特性研究

通过化学处理，将Ｒ－６４０、Ｒ－６Ｇ等激光染料掺入到聚甲基丙烯酸甲脂中制成塑料激光介质，研究了这种激光工作物质的有关激光特性。