液晶空间光调制器（LC-SLM）通过对液晶折射率的调制来实现对光程的控制，在自适应光学中起着重要的作用。文章梳理了国内外LC-SLM的发展现状，对LC-SLM的工作原理和相位标定原理进行了详细介绍，针对LC-SLM在自适应光学中的应用，对国内外LC-SLM关键技术研究状况进行了讨论，分析总结了西安理工大学在该领域的实验研究。最后展望了LC-SLM的应用前景。

A 60-mW solid-state deep ultraviolet (DUV) laser at 193 nm with narrow linewidth is obtained with two stages of sum frequency generation in LBO crystals. The pump lasers, at 258 and 1553 nm, are derived from a homemade Yb-hybrid laser employing fourth-harmonic generation and Er-doped fiber laser, respectively. The Yb-hybrid laser, finally, is power scaling by a 2 mm × 2 mm × 30 mm Yb:YAG bulk crystal. Accompanied by the generated 220-mW DUV laser at 221 nm, the 193-nm laser delivers an average power of 60 mW with a pulse duration of 4.6 ns, a repetition rate of 6 kHz, and a linewidth of ∼640 MHz. To the best of our knowledge, this is the highest power of 193- and 221-nm laser generated by an LBO crystal ever reported as well as the narrowest linewidth of 193-nm laser by it. Remarkably, the conversion efficiency reaches 27% for 221 to 193 nm and 3% for 258 to 193 nm, which are the highest efficiency values reported to date. We demonstrate the huge potential of LBO crystals for producing hundreds of milliwatt or even watt level 193-nm laser, which also paves a brand-new way to generate other DUV laser wavelengths.

An exceptional-point (EP) enhanced fiber-optic bending sensor is reported. The sensor is implemented based on parity-time (PT)-symmetry using two coupled Fabry-Perot (FP) resonators consisting of three cascaded fiber Bragg gratings (FBGs) inscribed in an erbium-ytterbium co-doped fiber (EYDF). The EP is achieved by controlling the pumping power to manipulate the gain and loss of the gain and loss FP resonators. Once a bending force is applied to the gain FP resonator to make the operation of the system away from its EP, frequency splitting occurs, and the frequency spacing is a nonlinear function of the bending curvature, with an increased slope near the EP. Thus, by measuring the frequency spacing, the bending information is measured with increased sensitivity. To achieve high-speed and high-resolution interrogation, the optical spectral response of the sensor is converted to the microwave domain by implementing a dual-passband microwave-photonic filter (MPF), with the spacing between the two passbands equal to that of the frequency splitting. The proposed sensor is evaluated experimentally. A curvature sensing range from 0.28 to 2.74 m^?1 is achieved with an accuracy of 7.56×10^?4 m^?1 and a sensitivity of 1.32 GHz/m^?1, which is more than 4 times higher than those reported previously.

光斑检测技术在现代科学研究与应用中扮演着重要角色，四象限探测器由于其具有探测灵敏度高、信号处理简单和抗干扰能力强等优点，在光斑检测技术中得到了广泛的应用，是捕获、跟踪和瞄准系统中的关键器件。首先介绍了光斑检测中常用的光斑模型和四象限探测器检测光斑原理，然后分析了国内外在四象限探测器检测光斑方面的研究成果，以及影响四象限探测器检测光斑精度的因素和常用的光斑检测算法，同时介绍了四象限探测器的光斑检测系统,包括光束对准检测系统、四象限探测器跟踪通信复合系统和微纳激光通信系统。最后，展望了光斑检测技术的发展前景。