针对无人机在复杂环境下受到多种威胁时的航迹规划问题, 提出一种改进的基于球面向量的粒子群优化算法(ISPSO)。利用融合压缩因子和异步变化学习因子的ISPSO算法, 通过粒子位置和速度同无人机转角和爬升角的对应关系, 高效地搜索无人机的构形空间, 找到成本函数最小的最优路径。为了评估ISPSO的性能, 从真实的数字高程模型地图中生成2个基准场景, 仿真结果表明, 该算法优于基于球面向量的粒子群算法。

Abstract: A π phase-shifted fiber Bragg grating theoretical model is established, and the effects of an asymmetric and symmetrical perturbation field on a phase-shifted fiber Bragg grating are investigated in this paper. The trends of wavelength shifting caused by effective refraction index of phase shift grating in symmetric and asymmetric acoustic field are investigated in detail. Then, the fiber laser acoustic sensors packaged in asymmetric and symmetrical structures are designed and tested, respectively. The results show that the acoustic response of the wavelength of the distributed feedback (DFB) fiber laser (FL) in an asymmetric packaging structure is much more sensitive than in that in the symmetrical structure. The sensor packaged in the asymmetrical structure has a better low frequency (0 Hz-500 Hz) performance and a higher sensitivity than that in the symmetrical structure, and the sensitivity is improved about 15 dB in average and 32.7 dB in maximum. It provides a new method to improve the sensitivity of the fiber acoustic sensor.

基于耦合模理论, 数值仿真了两种耦合结构(FW和WF)下的耦合损耗随锥形光波导芯层尺寸的变换规律; 进一步分析了两种耦合结构下锥形光波导端面粗糙度对其模式耦合损耗特性的影响, 表明不同模式其端面散射损耗不同; 实验结果表明, 锥形光波导的输入端芯层尺寸、输出端芯层尺寸及光波导长度, 对FW结构下的耦合损耗影响较小, 对WF结构下的耦合损耗影响较大。

Fiber laser hydrophones have got widespread concerns due to the unique advantages and broad application prospects. In this paper, the research results of the eight-element multiplexed fiber laser acoustic pressure array and the interrogation system are introduced, containing low-noise distributed feedback fiber laser (DFB-FL) fabrication, sensitivity enhancement packaging, and interferometric signal demodulation. The frequency response range of the system is 10 Hz-10 kHz, the laser frequency acoustic pressure sensitivity reaches 115 dB re Hz/Pa, and the equivalent noise acoustic pressure is less than 60μPa Hz^1/2. The dynamic range of the system is greater than 120 dB.

提出了一种利用均匀相位掩模板制作啁啾光纤光栅(FBG)的方法。在对光纤的扫描曝光过程中, 相位掩模板沿长度方向周期性抖动, 且抖动幅度随光栅扫描长度的变化而变化, 使FBG的相位随着掩模板位置的变化而变化, 实现了FBG周期的线性调制, 从而得到线性啁啾FBG。掩模板抖动振幅的变化规律决定了FBG的啁啾系数。设计了3种不同的相位掩模板抖动函数, 实验制作了不同啁啾量的FBG。

提出了一种基于准分子激光制备45°微反射镜的新方法──激光阶梯刻蚀法，介绍了该方法的工艺流程。通过优化参数制备了微反射镜样品，详细分析了样品参数对微镜反射性能的影响。利用微反射镜样品进行垂直耦合实验，深入讨论了影响系统损耗的主要因素。实验结果表明，微反射镜样品造成的损耗约为3.5 dB。该制备方法有望在大尺寸光波导互连背板耦合器件的研制中得到广泛应用。

A narrow linewidth laser configuration based on distributed feedback fiber lasers (DFB-FL) with eight wavelengths in the international telecommunication union (ITU) grid is presented and realized. In this laser configuration, eight phase-shifted gratings in series are bidirectionally pumped by two 980-nm laser diodes (LDs). The final laser output with over 10-mW power for each wavelength can be obtained, and the maximum power difference within eight wavelengths is 1.2 dB. The laser configuration with multiple wavelengths and uniform power outputs can be very useful in large scaled optical fiber hydrophone fields.

分别对Nufern公司和CorActive公司的光敏性Er/Yb共掺单模光纤采用直接紫外曝光方式制备了分布反馈和分布布拉格反射结构的短腔光纤激光器。实验结果表明：Er/Yb共掺光纤存在与温度有关的猝灭效应。在激光斜率效率测试过程中，当抽运功率达到一定值时，出现了激光输出功率陡然降低的现象。对激光器谐振腔进行辅助散热时，激光转化效率有所升高。通过对同一台激光器进行先后测量发现，再次测量得到的激光器效率总是低于制作完成即时测量的数值；在高抽运条件下，输出功率衰退和受温度影响的状况总是存在。

报道了通过Nd2O3掺杂实现对CaCu₃Ti₄O₁₂ (CCTO)介电陶瓷在太赫兹(THz)波段介电常数和损耗的调制。采用固相反应法制备了Nd₂O₃ 掺杂的CCTO 样品。结构分析表明Nd 离子掺杂不影响陶瓷的主晶相结构；形貌表征显示Nd 离子掺杂的CCTO 陶瓷晶粒尺寸随掺杂质量百分比增加而呈现先增大后减小的趋势，对晶粒有明显的细化作用；THz测试结果显示CCTO 的实介电常数与晶粒尺寸变化趋势相反；介电损耗和晶粒尺寸变化趋势相同。结果表明，通过Nd2O3掺杂调制CCTO 晶粒的大小，能够实现对THz波段的介电调制功能。