1.06μm激光辐照金盘靶的软X光转换

在１．０６μｍ激光辐照金盘靶实验中，利用坪响应Ｘ光二级管探测器测量了软Ｘ光能量（０．１－１．５ｋｅＶ）角分布，得到了软Ｘ光转换效率。实验条件：激光波长λＬ＝１．０６μｍ，ＥＬ＝６０－５００Ｊ，τｐｍ≈８００ｐｓ，ｆ／１．７，ＩＬ＝１０＾１＾３－１０＾１＾４Ｗ／ｃｍ＾２。实验结果表明：软Ｘ光能量角分粗略呈α＋ｂｃｏｓθ分布，软Ｘ光转换效率随激光强度的增加而降低。当靶面激光焦斑直径２３５μｍ，激光强度     

半导体激光泵浦的Nd：YVO4激光器的1.064μmy高效率连续输出

报道了半导体激光端面泵浦的Ｎｄ：ＹＶＯ４激光器获得线偏振的１．０６４μｍ激光高效率连续稳定输出，在半导体激光功率为１．５Ｗ时，获得连续输出功率为８３７ｍＷ的ＴＥＭ００模，激光器泵浦阈值功率为１４０ｍＷ，斜率效率达６１．５％，光－光转换效率达５６％，电－光转换效率达１５％。     

夜视像增强器(蓝光延伸与近红外延伸光阴极)的近期进展

２０世纪９０年代以来，夜视像增强器的研究主要朝着两个方向发展：一是研究对于探测、识别与确认沙漠地带或沙地景物有贡献的蓝光延伸（＜５５０ｎｍ）ＧａＡｓ负电子亲和势（ＮＥＡ）光阴极，光谱响应向短波长延伸，使光阴极灵敏度、光增益与鉴别率等性能大大优于标准三代管，从而形成“加强三代管”或所谓“四代管”，其探测性能较标准三代管高一倍；二是研究与夜天空辐射较为匹配、对１．０６μｍ激光有较高响应的光阴极，包括研究ＩｎＧａＡｓ、ＮＥＡ光阴极（１．０～１．３μｍ和１．５～２．０μｍ）和多碱光阴极（１．０～１．１μｍ）这三类近红外（ＮＩＲ）像管，可用于主被动夜视。本文综述了这几个方面的进展及其在夜视中的实际应用。     

光栅腔BBO光参量振荡器

报道０．５３２μｍ泵浦的光栅腔ＢＢＯ光参量振荡器的实验研究结果，在１．０２－１．０８μｍ可调谐范围内，其输出线宽小于１ｎｍ，参量转换效率为３．５％。     

半导体激光泵浦的Nd∶YVO_4激光器的1．064μm高效率连续输出

报道了半导体激光端面泵浦的Ｎｄ∶ＹＶＯ４激光器获得线偏振的１．０６４μｍ激光高效率连续稳定输出。在半导体激光功率为１．５Ｗ时，获得连续输出功率为８３７ｍＷ的ＴＥＭ００模，激光器泵浦阈值功率为１４０ｍＷ，斜率效率达６１．５％，光－光转换效率达５６％，电－光转换效率达１５％。     

单模光纤中Raman光放大

本文报道在单模光纤中，背向受激拉曼散射（ＢＳＲＳ）对通信光的光放大研究。所用泵浦源为声光０开关Ｎｄ￣（＋３）：ＹＡＧ激光器，工作波长１．０６４μｍ。信号源为ＩｎＧａＡｓＰ半导体激光器，工作波长１．３０μｍ。在１．３０μｍ处实现了Ｒａｍａｎ光放大，增益达１９．４ｄＢ以上，增益系数为２．３×１０￣（－１２）ｃｍ／ｗ。     

外腔锁模多量子阱二极管激光器

报道一种用作光通讯光源的外腔锁模多量子阱结构半导体激光器，其脉冲宽度２～５ｐｓ，波长调谐范围为１．５２～１．５７μｍ，锁模频率０．５～１．０ＧＨｚ平均输出光功率为１ｍＷ。     

半导体激光泵浦Nd：YVO4激光器的1.34μm输出特性

报道了半导体激光泵浦Ｎｄ：ＹＶＯ４激光器在１．３４μｍ的输出特性，当入射的泵浦光功率为５１５ｍＷ时，最大１．３４μｍ激光输出功率达１５７ｍＷ，光－光转换效率为３０．５％，研究了激光器的纵模特性及弛豫噪声与泵浦功率的关系，发现不同的纵模具有各自不同的弛豫振荡频率。     

激光二极管抽运Nd∶YVO_4晶体1342nm和671nm激光器研究

报道了激光二极管抽运的Ｎｄ∶ＹＶＯ４晶体１３４２和６７１ｎｍ激光特性．１３４２ｎｍ激光最大输出功率为１７５Ｗ，光光转换效率为３２１％，斜效率为４３％．利用Ⅰ类非临界相位匹配ＬＢＯ晶体腔内倍频，当输入抽运功率为６Ｗ时，获得功率为５０２ｍＷ的６７１ｎｍ激光输出，光光转换效率超过８３％；当６７１ｎｍ激光输出功率为４００ｍＷ时，短期的不稳定度小于２％．     

1.55μmSi1—xGex光波导在Si1—xGex／Si多量子阱探测器集成的优…

对１。５５μｍ波长的Ｓｉ１－ｘＧｅｘ光波导和Ｓｉ１－ｘＧｅｘ／Ｓｉ多量子阱红外探测器的集成器件结构进行了系统的分析和优化设计。优化结果为：１）对Ｓｉ１－ｘＧｅｘ光波导，Ｇｅ含量ｘ＝０．０５，脊宽，高和腐蚀深度分别为８，３和２．６μｍ，２）对ＳＩ１－ｘＧｅｘ／Ｓｉ多量子阱红外探测器，Ｇｅ含量ｘ＝０．５，探测器由厚度为５５０ｎｍ，２３个周期的６ｎｍＳｉ０．５ＧＥ０．５＋１８ｎｍＳｉ组成，长度约２ｍｍ。     

Analysis of High Power Millimeter Wave Waveguide Mode Converters with Input Mode Mixture

Based on the coupled mode theory, this paper presents the study on the influence of input mode mixture in circular oversized waveguide mode converters. Three kinds of commonly used waveguide mode converters, including the waveguide mode converters with varying wall radius or small axis perturbations, and the waveguide mode converters with bent structures, are taken as the examples. The results show that the spurious input modes do not simply superimpose onto the output modes, and in some cases they may deteriorate the conversion efficiency for the main output mode. Methods for transforming such spurious input mode mixture simultaneously into the main output mode are also presented in this paper.     

Polarization Mode Dispersion Probability Distribution for Arbitrary Mode Coupling

The probability distribution of the differential group delay for arbitrary mode coupling is simulated with Monte-Carlo method. Fitting the simulation results, we obtain probability distribution function for arbitrary mode coupling.     

单模光纤中偏振模色散的仿真模型

利用琼斯矩阵法研究了长单模光纤中偏振模色散的仿真模型.考虑到偏振模色散的随机性,该模型中单模光纤被看作是一系列短双折射光纤段的级联,相邻两段之间耦合角是随机的.研究结果表明,当短双折射光纤段等长时,偏振模色散呈现随波长周期性变化的特点;不符合实际情况.当短双折射光纤段不等长且服从高斯分布时,周期性逐渐消失;当其长度均方差为均值的20%,周期性完全消失.最后比较了偏振模色散的时域统计特性.取短双折射光纤段的长度服从高斯分布且均方差为均值的20%,偏振模色散的统计特性接近于实际分布.因此得出结论:为了正确估计偏振模色散的影响,在单模光纤的级联模型中,短双折射光纤段的长度应服从高斯分布,均方差为其均值的20%.     

Mode Suppression Phenomenon in a Mode Splitting He-Ne Laser

The mode competition is significant in laser physics and applications. A priority frequency will suppress, in competition, a potential frequency within gain profile, and this becomes more obvious with greatly decreasing the spacing of the two frequencies. The small spacing is produced by splitting one mode into two orthogonally polarized frequencies in a 0. 6328 μm He-Ne laser with a short cavity length (150 mm long). By tuning the cavity length, the intensities of the two frequencies (e-mode and o-mode) under a ariety of frequency spacings is measured. The suppression bandwidth for the potential mode is up to several hundreds of MHz and changes with the frequency spacing of the pair of frequencies. The intensities for the two frequencies are vary oppositely.     

Mode Suppression Phenomenon in a Mode Splitting He-Ne Laser

The mode competition is significant in laser physics and applications. A priority frequency will suppress, in competition, a potential frequency within gain profile, and this becomes more obvious with greatly decreasing the spacing of the two frequencies. The small spacing is produced by splitting one mode into two orthogonally polarized frequencies in a 0. 6328 μm He-Ne laser with a short cavity length (150 mm long). By tuning the cavity length, the intensities of the two frequencies (e-mode and o-mode) under a ariety of frequency spacings is measured. The suppression bandwidth for the potential mode is up to several hundreds of MHz and changes with the frequency spacing of the pair of frequencies. The intensities for the two frequencies are vary oppositely.     

Mode order converter

We report experimental results with a simple mode order converter for dielectric slab waveguides. In particular we have shown conversion of higher order modes to the only mode of a monomode waveguide.     

Mode transformer for miniaturized optical circuits

A novel mode transformer was fabricated that transforms a modal area by a factor of 100. Using the mode transformer improves the efficiency of mode transformation by an order of magnitude compared with that when no mode transformer is used. With this mode transformer, input-output coupling of miniaturized, on-chip integrated optical circuits to external optical fibers is achieved with low loss. The mode transformer's design, fabricated in silicon, is scalable to virtually any waveguide size, facilitating continuous miniaturization in silicon optoelectronics.     

初始点火条件引起的三维旋转爆震波单/双波传播模式

在不同工况下,旋转爆震波能够以单波、双波、多波模式进行传播.但在同一工况下,是否存在不同模式的稳定传播爆震波还有待进一步研究.基于Euler方程,耦合氢气/空气的有限化学反应速率模型,并采用高分辨率的5阶有限差分格式WENO-PPM5离散对流项,对三维旋转爆震波进行了数值模拟.计算结果表明,在同一特定工况下,旋转爆震波能够以两种不同的传播模式稳定传播,即单波模式和双波模式.详细地对比了两种传播模式下的流场特征、爆震波传播特性、推力性能等.在同一工况下,两种传播模式的爆震波周向传播速度相差不多,但双波模式的频率约为单波模式的2倍;双波模式下质量流量、比冲、推力的平均值均略高于单波模式;且双波模式的可燃混气层高度约为单波模式的1/2,这有助于缩小旋转爆震发动机的长度,使之更加紧凑.      

不同模式耦合下偏振模色散几率分布的研究

研究了偏振模色散的统计特性,在不同模式耦合条件下,应用蒙特-卡罗方法模拟偏振模色散矢量的几率分布,并对模拟结果进行了函数拟合。发现随着耦合次数增加差分群时延的几率分布从一个类似δ函数分布逐渐过渡到麦克斯韦分布;在一定的耦合下,几率分布可以呈现高斯分布。对偏振模矢量的两个方向余弦进行统计分析,发现随着耦合次数的增加,偏振模矢量两个方向余弦函数的分布从高斯分布和δ函数分布都变为均匀分布。     

Mode competition in multi-core fiber amplifier

3D beam propagation numerical code and a newly developed optical mode solver were implemented for studies on the recently experimentally realized Yb fiber amplifier with 7-core hexagonal structure. It was found that the launched seven single-frequency beams matched with the cores converge to a wave field with permanently diminishing space beating patterns, but the result is sensitive to phases of separate beams. Namely, at a spread of phases of individual beams within a few tenths of radian, the convergence of the wave field to the in-phase mode is observed, while at phases random spread on the order of π the out-of-phase mode is dominating. Such behavior is observed at strong gain saturation in the cores. Both effects take place even if the guiding index of the cores fluctuates within a limited range. The mode solver predicts that the in-phase mode has the minimal small signal gain, and the gain of the out-of-phase mode is maximal one. This fact proves that there is no strict correlation between modal gains and amplification in strong saturated multi-core fiber. The smaller core index step significantly improves the convergence of the amplified radiation to the in-phase mode. An approach to the waveguide structure tailoring is described which assures the single in-phase mode stability.