平面交叉型微透镜阵列的制作及成像特性研究

介绍了采用光刻离子交换工艺制作平面交叉型微透镜阵列的方法。利用积分形式的光线方程式讨论了平面交叉型微透镜的近轴光学特性，研究了微透镜的光线轨迹方程式和一些重要的近轴成像特性，利用ABCD定理得到了平面交叉型微透镜像距、焦距、像高、横向放大率和主平面位置的数学表达式，焦距的理论计算结果和实验数据吻合得很好。

掺铒磷酸盐玻璃离子交换波导表面保护的研究

对离子交换波导制备过程中掺铒磷酸盐玻璃表面的侵蚀问题进行了研究，分析了产生侵蚀的原因，提出镀K9玻璃薄膜的方法，对掺铒磷酸盐玻璃表面进行保护．采用光学显微镜和原子力显微镜对波导表面特性进行了表征。同时对平板波导的光学特性进行了测试．研究表明K9玻璃薄膜不仅能够对掺铒磷酸盐玻璃起到保护作用，同时允许交换离子透过进入磷酸盐玻璃形成波导层．

Characteristics of 980/1550 nm WDM coupler based on planar curved waveguides

A wavelength division multiplexer (WDM) for 980/1550 nm based on planar curved waveguide coupler (CWC) is proposed. Compared with conventional parallel straight waveguide coupler (SWC), this structure has more flexibility with two variable parameters of bending radius R and minimum edge-to-edge spacing do, which are the two main parameters for the splitting ratio of coupler and decrease the complexity of device design and fabrication. Based on coupled mode theory (CMT) and waveguide theory, R and do of the WDM CWC are designed to be R = 13.28 m and d(0) = 4.39 mu m. The contrast ratio (CR) and insertion loss (IL) for 980 and 1550 nm are CR1 = 24.62 dB, CR2 = 24.56 dB and IL1 = 0.014 dB, IL2 = 0.015 dB, respectively. The 3D beam propagation method (BPM) is used to verify the validity of the design result. The influence of R and d(0) variations on the device performance is analyzed. For CR > 20 dB, the variation ranges of R and d(0) should be within -0.10 to +0.44 m and -0.05 to + 0.02 mu m, respectively. (c) 2006 Elsevier GmbH. All rights reserved.

K9玻璃薄膜对离子交换磷酸盐玻璃波导表面保护的优化研究

采用镀K9玻璃薄膜方法来解决离子交换掺铒磷酸盐玻璃波导表面的侵蚀问题,对K9玻璃薄膜的厚度进行了优化研究。测量分析了样品的荧光光谱和荧光寿命,采用光学显微镜和棱镜耦合技术对不同K9玻璃薄膜厚度下制备波导的表面形貌和导光特性进行了表征和测试。结果表明,与掺铒磷酸盐玻璃原材料相比,镀K9玻璃薄膜后荧光光谱保持不变,荧光寿命稍有下降(约0.2 ms);K9玻璃薄膜的厚度在60~80 nm的范围内保护效果最佳。为下一步制备掺铒有源玻璃光波导器件奠定了良好的实验基础。

基于电光材料的光学相控阵技术研究进展

综述了基于电光材料的光学相控阵(OPA)的研究进展。介绍了光学相控阵技术的基本原理以及不同电光材料(铌酸锂电光晶体,AlGaAs光波导,液晶和掺镧锆钛酸铅(PLZT)电光陶瓷)光学相控阵技术的基本构想和涉及的关键技术;着重介绍近年来基于PLZT电光陶瓷材料光学相控阵技术的发展情况以及在这方面的最新研究成果,包括单级相控阵、级联相控阵、不同电极结构(表面电极和上下电极结构)相控阵技术等;最后简要介绍了光学相控阵技术在激光雷达等军事领域中的应用。

Approximate analytical description for fundamental-mode fields of graded-index fibers: Beyond the Gaussian approximation

An approximate analytical description for fundamental-mode fields of graded-index fibers is explicitly presented by use of the power-series expansion method, the maximum-value condition at the fiber axis, the decay properties of fundamental-mode fields at large distance from the fiber axis, and the approximate modal parameters U obtained from the Gaussian approximation. This analytical description is much more accurate than the Gaussian approximation and at the same time keep the simplicity of the latter. As two special examples, we present the approximate analytical formulas for the fundamental-mode fields of a step profile fiber and a Gaussian profile fiber, and we find that they are both highly accurate in the single-mode range by comparing them with the corresponding exact solutions.

Prism coupling of ultrashort light pulses into waveguides

We discuss coupling of ultrashort light pulses into waveguides by use of a prism waveguide coupler configuration. Theoretical analysis indicates that an extra loss induced by the short coherence times of ultrashort pulses, which has a strong effect on the reflected light and the optimum coupling condition, appears in the waveguide. Numerical simulations show that the reflectance strongly depends on the coherence times of ultrashort pulses. A method for realizing optimum coupling by compensating for the extra loss is proposed as well in this paper. A preliminary experiment of employing ultrashort pulses with different coherence times was carried out, and good agreement between theory and experiment was obtained. (c) 2006 Optical Society of America.

Field and dispersion properties of subwavelength-diameter hollow optical fiber

We have investigated the basic properties of subwavelength-diameter hollow optical fiber with exact solutions of Maxwell's equations. The characteristics of modal field and waveguide dispersion have been studied. It shows that the subwavelength-diameter hollow optical fibers have interesting properties, such as enhanced evanescent field, local enhanced intensity in the hollow core and large waveguide dispersion that are very promising for many miniaturized high performance and novel photonic devices. (C) 2007 Optical Society of America.

高功率激光装置前端系统激光脉冲的时间整形及修正技术

针对激光惯性约束聚变实验研究对高功率激光驱动器前端系统复杂时间形状种子激光脉冲的需求, 应用孔径耦合带状线集成波导整形系统设计了满足需要的前端整形激光脉冲。用一种新方法精确计算了孔径耦合带状线电脉冲整形器的耦合系数和孔径宽度的数值关系, 并针对高衬比度整形激光脉冲的需求, 提出了高衬比度双极型集成波导整形系统方案。由该系统可以得到100 ps脉冲前沿、1～3 ns脉冲宽度可调、高衬比度(大于100∶1)、光滑无纹波调制、可精确满足神光II八路及第九路装置需求的前端整形激光脉冲。

基于电光调制的激光光谱整形技术

提出了一种新型的基于电光调制的激光光谱整形方案，该整形技术可以减轻啁啾脉冲放大系统中的增益窄化效应。傅立叶变换限的宽带种子激光脉冲通过光学展宽器线性展宽后，耦合到加载有整形电脉冲的集成波导调制器中进行整形，整形电脉冲由孔径耦合带状线电脉冲发生器产生。由于线性啁啾脉冲时间-频率的直接对应关系，在时域内对宽带种子激光脉冲整形，其光谱也得到了同样形状的整形。模拟了整形光谱形状，相应的整形电脉冲波形，分析了该整形技术的光谱整形分辨率，以及整形过程中引入的相位畸变。

Electromagnetic fields and transmission properties in tapered hollow metallic waveguides

We analyze the electromagnetic spatital distributions and address an important issue of the transmission properties of spherical transverse-electric (TE) and transverse-magnetic (TM) eigenmodes within a tapered hollow metallic waveguide in detail. Explicit analytical expressions for the spatital distributions of electromagnetic field components, attenuation constant, phase constant and wave impedance are derived. Accurate eigenvalues obtained numerically are used to study the dependences of the transmission properties on the taper angle, the mode as well as the length of the waveguide. It is shown that all modes run continuously from a propagating through a transition to an evanescent region and the value of the attenuation increases as the distance from the cone vertex and the cone angle decrease. A strict distinction between pure propagating and pure evanescent modes cannot be achieved. One mode after the other reaches cutoff in the tapered hollow metallic waveguide as the distance from the cone vertex desreases. (C) 2008 Optical Society of America

改善高功率激光二极管阵列光束质量的一种新方法

根据波导模理论,推导了高功率激光二极管阵列的远场分布,根据其分布特点,设计了一种离轴外腔.运用这种外腔,在工作电流为17A时,光束的束宽积从自由运转时的1100mm.mrad减小到128mm.mrad,二极管阵列的光束质量提高了8.5倍左右,输出功率约为自由运转时的75%.

侧面泵浦的短矩形掺钕磷酸盐玻璃光纤激光器

利用光纤－波导耦合器技术侧面泵浦一根4厘米长的短光纤，我们研制得到了一个红外波长的光纤激光器。该激光器的增益介质是横截面为矩形的掺钕磷酸盐玻璃光纤，其纤芯横截面尺寸为1.5×0.5 毫米，数值孔径为0.2。单横模激光可以通过该矩形光纤的增益-导引效应来获得。最大的激光输出功率为1.05瓦，斜率效率为10％。

初始啁啾对光纤中传播的飞秒光孤子的影响

采用分步傅里叶变换作为数值模拟的方法，以二阶飞秒光孤子和基态飞秒光孤子为例，讨论了初始啁啾对光纤中传播的飞秒光孤子的时域特征和频谱结构的影响，概括出如下的结论：初始啁啾通过影响飞秒光孤子谱线的红移，而对飞秒光孤子由拉曼效应引发的脉冲延迟产生较大影响，正的初始啁啾使脉冲延迟加剧，负的初始啁啾使脉冲延迟减小。

硬边非稳腔平面波导激光器的光束特性

基于衍射理论和坐标变换,采用数值模拟的方法分析了硬边非稳腔平面波导激光器的光束特性,研究了存在非均匀抽运和增益饱和时,输出激光的光束质量.在端面抽运和边缘抽运时,比较了正支和负支非稳腔的输出光束特性.结果表明：利用优化的离轴硬边非稳腔可以得到近衍射极限的输出.在相同的抽运不均匀性情况下,对于边缘抽运和端面抽运,正支非稳腔的光束质量因子M^2分别为3.9和2.3,而相同条件下负支非稳腔的M^2因子为1.8和1.7.