A method of spectrum estimation based on the genetic simulated annealing (GSA) algorithm is proposed, which is applied to retrieve the three-dimensional wind field of typhoon Nangka observed by our research group. Compared to the genetic algorithm (GA), the GSA algorithm not only extends the detection range and guarantees the accuracy of retrieval results but also demonstrates a faster retrieval speed. Experimental results indicate that both the GA and GSA algorithms can enhance the detection range by 35% more than the least squares method. However, the convergence speed of the GSA algorithm is 17 times faster than that of the GA, which is more beneficial for real-time data processing.

为充分利用高光谱影像中蕴含的空谱特征，提出了一种半监督空谱局部判别分析的高光谱影像特征提取算法（S₄LFDA）。鉴于高光谱数据集具有空间一致性，首先将像元进行空间重构，保存高光谱数据的近邻关系；其次引入光谱信息散度重构像元间的相似度；为了充分利用大量无标签样本提高算法性能，采用模糊C均值聚类算法对样本进行聚类分析得到伪标签；然后通过增加规范化项到局部力导引算法（FDA）的类内散度矩阵和类间散度矩阵中，以此保持无标签样本的聚类结构一致性；最后通过局部FDA算法来保持有标签样本类间散度最大化和类内散度最小化并求解最佳投影向量。S₄LFDA算法既保持了数据集在光谱域的可分性，又保持了像元在空间区域内的近邻关系，合理利用有标签样本及无标签样本，提高了算法的分类性能。在Pavia University和Indian Pines数据集上进行实验，总体分类精度达到95.60%和94.38%。与其他维数约简算法相比，该算法有效提高了地物分类性能。

The emergent two-dimensional (2D) material, tin diselenide (SnSe₂), has garnered significant consideration for its potential in image capturing systems, optical communication, and optoelectronic memory. Nevertheless, SnSe₂-based photodetection faces obstacles, including slow response speed and low normalized detectivity. In this work, photodetectors based on SnS/SnSe₂ and SnSe/SnSe₂ p?n heterostructures have been implemented through a polydimethylsiloxane (PDMS)?assisted transfer method. These photodetectors demonstrate broad-spectrum photoresponse within the 405 to 850 nm wavelength range. The photodetector based on the SnS/SnSe₂ heterostructure exhibits a significant responsivity of 4.99 × 10³ A?W^?1, normalized detectivity of 5.80 × 10¹² cm?Hz^1/2?W^?1, and fast response time of 3.13 ms, respectively, owing to the built-in electric field. Meanwhile, the highest values of responsivity, normalized detectivity, and response time for the photodetector based on the SnSe/SnSe₂ heterostructure are 5.91 × 10³ A?W^?1, 7.03 × 10¹² cm?Hz^1/2?W^?1, and 4.74 ms, respectively. And their photodetection performances transcend those of photodetectors based on individual SnSe₂, SnS, SnSe, and other commonly used 2D materials. Our work has demonstrated an effective strategy to improve the performance of SnSe₂-based photodetectors and paves the way for their future commercialization.

The 975 nm multimode diode lasers with high-order surface Bragg diffraction gratings have been simulated and calculated using the 2D finite difference time domain (FDTD) algorithm and the scattering matrix method (SMM). The periods and etch depth of the grating parameters have been optimized. A board area laser diode (BA-LD) with high-order diffraction gratings has been designed and fabricated. At output powers up to 10.5 W, the measured spectral width of full width at half maximum (FWHM) is less than 0.5 nm. The results demonstrate that the designed high-order surface gratings can effectively narrow the spectral width of multimode semiconductor lasers at high output power.

光学下变频技术可将宽频带内全部电磁信号同时下变频到低频区间进行接收，是一种新型宽频带电磁环境快速接收技术。但是，获取的光学下变频信号中包含源个数未知、带宽不同的多种信号，现有信号分离方法需要获知源信号的个数，且无法同时分离窄带信号和宽带信号。为实现对光学下变频信号的自动分离，提出了一种基于变分模态分解（VMD）自适应模态重组的光学下变频信号分离方法。通过频谱分割因子和频谱包络检测，对光学下变频信号的VMD过分解模态进行自动重组和信号重组模态提取，实现光学下变频信号分离。对于包含普通脉冲信号、宽带码分多址（WCDMA）信号和线性调频脉冲信号的光学下变频信号，可自动实现对三种信号的分离，且与原信号的相似系数均高于0.97。实验结果表明，所提及方法在分离光学下变频信号时无需获知源信号的个数，并能同时分离具有不同带宽的多种源信号。

针对复杂电磁环境和复杂大型系统电磁干扰测量参数、测量点位及测量工况多的特点，采用传统扫频式频域测量方法具有代价高、耗时长等现实问题，提出了一种低频电磁干扰的多通道时域快速测量与信号计算方法，并研制出低频电磁干扰多通道时域快速测量系统，实验验证表明提出的测量、计算方法和研制出的测量系统可以准确得到复杂电磁环境和大型系统的低频电磁干扰特性，且测量速度快、成本低。