优化波导短程透镜的研究

本文报导优化波导短程透镜器件技术。文中用我们给出的无曲率奇点非球面波导短程透镜的最优理论设计，研制出优化波导短程透镜。实验测试表明短程透镜在通光径8mm内无球差，对4mm宽平面波束，其焦点束斑的4μm。这是先进的国际器件指标。     

优化的波导短程透镜研究

对光波导短程透镜进行优化。在无曲率奇点理想波导短程透镜的基础上，选取一般形式卷边函数，以无弯曲损耗为目标，讨论了透镜过渡区不同卷边函数形式的曲率分布，选取了最优卷边函数并给出透镜母线的特解。经过数值计算得到了优化的理想波导短程透镜的母线函数数值，完成了非球面面型的精细加工，研制出优化的理想波导短程透镜。实验测试结果表明，短程透镜在通光孔径8mm内消球差，对4mm宽的平面波束，焦距20mm的短程透镜，其焦点束斑宽度小于4μm。     

理想波导短程透镜的卷边函数与特解

在无曲率奇点理想波导短程透镜的基础上，本文选取一般形式卷边函数，以降低弯曲损耗为目的，讨论了透镜卷边区不同卷边形式的曲率分布，优化了卷边函数并给出特解。     

无曲率奇点的光波导短程透镜的设计

在Ｓｏｔｔｉｎｉ等人提出的求解非球面光波导短程透镜一般解析方法的基础上，研究了卷边函数对透镜旋转母线曲率的影响。指出具有连续二阶导数的母线，可有效地消除曲率奇点，从而在理论上能够减小由于波导弯曲造成的导光损耗。基于这种观点，提出了一种新的卷边函数，求得了透镜轮廓的表达式，进而求得了透镜深度，并与Ｓｏｔｔｉｎｉ等人的解进行了比较。     

四种解析解设计的短程透镜卷边对损耗的影响

根据光波导短程透镜母线曲率半径与光传输损耗的关系,利用数值计算的方法,通过计算不同母线参数条件下,四种解析解设计的短程透镜母线曲率半径,研究比较了短程透镜卷边对其损耗的影响,得出了短程透镜损耗与其有效区半径关系的曲线图,发现透镜凹面半径一定时,有效区半径越小,即卷边越大时,光传输损耗越小;短程透镜的解析改进解和最优解设计的透镜卷边存在曲率奇点.并由此得出了四种解析解设计的短程透镜有效区半径选取原则及其满足低损耗条件的取值范围.     

短程透镜-光栅型集成波分复用器

制备了一种短程透镜——光栅型集成光学波分复用器。本文简述了波分复用器的原理和制备工艺,描述了其中的关键元件光波导光栅和光波导透镜的设计及特性测量,给出了波分特性的实验结果.     

无球差非球面短程透镜的研究

用光线追迹迭代法和解析法设计无球差非球面波导短程透镜的母线,用单点金刚石超精加工和凹面波导制备工艺,研制成孔径和有效孔径分别为8和6mm的LiNbO3导短程透镜.实验表明,器件在有效孔径内无球差;对4mm宽的输入平面波光束,焦点衍射光斑半宽度为4μm;透镜插入损耗为～1dB.     

波导短程透镜的实验研究

波导透镜是集成光路〔IO〕中的最基本元件,它在IO中的作用类似体光学光路中的透镜.IO光信号处理系统如集成光学声光频谱分析器、导波声光卷积器、相关器、调频脉冲压缩器和矩阵乘法器等.系统中都需要用波导透镜.波导短程透镜较其它形式的波导透镜具有孔径大、旋转对称、无色差和插入损耗小的特点,所以特别引人注意.     

球面波导短程透镜的球差

本文是对球面波导短程透镜球差的初步研究,报道一种测量球差的方法,对玻璃波导球面短程透镜的球差实验测量表明,测量结果与理论预计基本相符。     

光波导短程透镜焦点特性的分析

利用波导短程透镜的几何光学性质, 给出了短程透镜的等效光线追迹图和相位传递函数, 得到短程透镜焦点的模场分布表达式. 理论得出的焦斑光强分布和实验测得的光强分布一致.     

超辐射发光二极管的输出特性

利用多模速率方程组的解析解对超辐射发光二极管的输出特性进行了研究。在此基础上数值模拟了衡量超辐射发光二极管工作的重要参量发输出线宽和输出功率等随端面反射率的变化，并且分析了它们之间的相互关系，实验结果与理论大致相符。     

Short-wavelength InAlGaAs/AlGaAs quantum dot superluminescent diodes

This paper reports the fabrication of J-shaped bent-waveguide superluminescent diodes utilizing an InAlGaAs/AlGaAs quantum dot active region. The emission spectrum of the device is centred at 884 nm with a full width at half maximum of 37 nm and an output power of 18 mW. By incorporating an Al composition into the quantum dot active region, short-wavelength superluminescent diode devices can be obtained. An intersection was found for the light power-injection current curves measured from the straight-waveguide facet and the bent-waveguide facet, respectively. The result is attributed to the conjunct effects of the gain and the additional loss of the bent waveguide. A numerical simulation is performed to verify the qualitative explanation. It is shown that bent waveguide loss is an important factor that affects the output power of J-shaped superluminescent diode devices.     

半导体超辐射发光管自发发射因子的估算

自发发射因子β是半导体光电器件的重要参数,在以往对超辐射发光管的特性分析,特别是应用速率方程对超辐射器件的光强进行估算时,多沿用与超辐射发光器件相应结构激光器的β因子,由于两者的光输出特性不同,这种沿用不仅会造成β因子物理意义上的混乱,而且也给超辐射器件光电特性的分析带来了较大的误差。对超辐射发光管的自发发射因子β进行了讨论,提出了平均自发发射因子的概念,并对增益导引及折射率导引的β因子进行了估算     

大功率短波长InAlGaAs/AlGaAs量子点超辐射发光管

为了满足超辐射发光管的短波长应用,采用InAlGaAs/AlGaAs量子点有源区和干法刻蚀工艺制备了短波长弯曲波导超辐射发光管。在1.6A脉冲电流注入下,器件峰值输出功率为29mW,中心波长为880nm,光谱半高宽为20.3nm。比较了干法刻蚀工艺和湿法腐蚀工艺对超辐射发光管器件性能的影响。在1.6A脉冲电流注入下,湿法腐蚀制备的器件峰值输出功率仅为7mW。与湿法腐蚀相比,干法刻蚀可以精确控制波导形状和参数,降低波导损耗,有效增大器件输出功率。     

InAs/GaAs submonolayer quantum-dot superluminescent diodes with active multimode interferometer configuration

With a chirped InAs/GaAs SML-QD (quantum dot) structure serving as the active region, the superluminescent diodes emitting at wavelength of around 970nm are fabricated. By using an active multimode interferometer configuration, these devices exhibit high continue-wave output powers from the narrow ridge waveguides. At continue-wave injection current of 800mA, an output power of 18.5mW, and the single Gaussian-like emission spectrum centered at 972nm with a full width at half maximum of 18nm are obtained.     

Comparison of two kinds of AlGaAs terraced substrate inner stripe superluminescent diodes

We report on two kinds of AlGaAs terraced substrate inner stripe superluminescent diodes: those with SiO _x antireflection coatings, and those with unpumped absorbing regions. The devices were fabricated by one-step liquid phase epitaxy. Both kinds of devices suppress stimulating oscillation effectively. The characteristics of the diodes with antireflection coatings are better than those with unpumped absorbing regions. The spectral width of the diodes with antireflection coatings is over 23 nm, the output power is about 7 mW, the modulation depth is less than 5%, and the horizontal divergence angle is smaller than 10–15°.     

Realization of extremely broadband quantum-dot superluminescent light-emitting diodes by rapid thermal-annealing process

The first demonstration, to our knowledge, of the creation of ultrabroadband superluminescent light-emitting diodes using multiple quantum-dot layer structure by rapid thermal-annealing process is reported. The device exhibits a 3 dB emission bandwidth of 146 nm centered at 984 nm with cw output power as high as 15 mW at room temperature corresponding to an extremely small coherence length of 6.6 microm.     

Graded tensile-strained bulk InGaAs/InP superluminescent diode with very wide emission spectrum

A kind of novel broad-band superluminescent diodes (SLDs) using graded tensile-strained bulk InGaAs is developed. The graded tensile-strained bulk InGaAs is obtained by changing only group-Ⅲ trimethylgallium source flow during low-pressure metal organic vapor-phase epitaxy. At the injection current of 200mA, the fabricated SLDs with such structure demonstrate full-width at half-maximum spectral width of 106 nm and the output light power of 13.6 mW, respectively.     

Analysis of the Characteristics of Laser and Superluminescent Diodes

It is shown that superluminescent diodes rank below laser diodes in energy characteristics, but they have a wider emission spectrum and lower noise level. The amplitude-frequency and noise characteristics of the laser diode correlate with each other, whereas there is no such correlation for the superluminescent diode. The photon density distribution along the active area is more homogeneous for the laser diode than for the superluminescent one. Presented at the 5th International Scientific-Technical Conference “Quantum Electronics,” November 22–25, 2004, Minsk, Belarus. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 689–693. September–October, 2005.     

Simple method for estimating shape functions of optical spectra

A simple method for estimating shape functions of optical spectra is proposed, based on the numerical correlation with an assumed optical spectrum composed of a central main rectangular component and two right-angled triangular wings on either side of the main component. The degrees of correlation between observed and assumed spectra were examined using spectral and coherence widths of those spectra and pulsewidths of Fourier-transform-limited pulses calculated from those spectra. By using this method, shape functions of output spectra from superluminescent diodes and a self-pulsating laser diode were evaluated in detail over a relatively wide injection current range beyond their rated currents.