Nonlinear compression has become an obligatory technique along with the development of ultrafast lasers in generating ultrashort pulses with narrow pulse widths and high peak power. In particular, techniques of nonlinear compression have experienced a rapid progress as ytterbium (Yb)-doped lasers with pulse widths in the range from hundreds of femtoseconds to a few picoseconds have become mainstream laser tools for both scientific and industrial applications. Here, we report a simple and stable nonlinear pulse compression technique with high efficiency through cascaded filamentation in air followed by dispersion compensation. Pulses at a center wavelength of 1040 nm with millijoule pulse energy and 160 fs pulse width from a high-power Yb:CaAlGdO₄ regenerative amplifier are compressed to 32 fs, with only 2.4% loss from the filamentation process. The compressed pulse has a stable output power with a root-mean-square variation of 0.2% over 1 hour.

利用溶剂热法制备了六角相NaYF₄∶20%Yb，2%Er@NaYF₄@NaYbF₄∶0.5%Tm@NaYF₄多层核壳结构稀土掺杂上转换纳米粒子，研究其在低温场（10~295 K）及980 nm激发下分别来自于Er³⁺的绿色与红色以及Tm³⁺的蓝色发光的上转换发光性质。结果显示，绿光强度随温度升高呈现出先增后降的变化趋势，而蓝光强度随温度升高呈现热衰减的趋势。本工作利用发光强度比的测温方法实现了精准的温度测量，相对灵敏度可达3.2%·K^-1。并通过改变外层发光壳层的厚度调节发光强度比，进一步应用于低温场光学防伪。

悬丝摆式加速度计具有小型化、大量程和抗冲击的特点，在航空航天领域得到广泛的应用。其底座与摆组件的精密装配，目前仍以人工装配为主，具有装配精度差、悬丝张紧力不易控制，人工焊接时焊接参数难以保证、焊点质量不佳等问题，导致产品的良品率较低。为此，研发了一套悬丝摆式加速度计底座组件自动装配与焊接设备。根据零件特点与装配环境，采用视觉与力觉反馈控制，实现底座与摆组件位姿和悬丝张紧力的自动调整。基于C++语言，开发了分层架构的控制软件。设计温度反馈控制的焊接工艺流程与焊接策略，并通过有限元仿真与焊接实验进行验证。实验结果表明：该设备可实现自动装配与焊接功能，底座组件的装配精度与焊接质量符合技术指标要求，提高了产品质量。

Nonlinear frequency conversion of wavelength agile and high-power random fiber lasers can provide a promising way to generate continuous-wave (CW) visible and mid-infrared (MIR) light with unique properties such as the continuous modeless spectrum, low temporal/spatial coherence, and high temporal stability. Here, we report a dual-wavelength switchable and tunable random Raman fiber laser (RRFL) based on a phosphosilicate fiber that has two Raman gain peaks for the first time and demonstrate its superior capability to generate widely tunable CW visible and mid-infrared light via nonlinear frequency conversions. By using the combination of a tunable pump and two tunable gratings in Littrow configuration that can provide separated point feedback for the two Stokes wavelengths corresponding to silica- and phosphorus-related Raman peaks, the spectrum of an RRFL can be flexibly manipulated for the aim of nonlinear frequency conversions, including single-wavelength tunable emission at the 1.1 μm or 1.2 μm band for second-harmonic generation (SHG), dual-wavelength simultaneously tunable emission at the 1.1 μm and 1.2 μm bands for the sum-frequency generation (SFG), and dual-wavelength separation tunable emission for difference-frequency generation (DFG). As a result, with the combination of SHG and SFG in a periodically poled lithium niobate crystal array, we experimentally demonstrate the broadest tuning range (560–630 nm) of visible light generated from an RRFL, to the best of our knowledge. The tunable MIR light in the range of 10.7–12.3 μm is also demonstrated through DFG of an RRFL operating in separation tunable dual-wavelength emission mode in a BaGa4Se7 (BGSe) crystal, which is the first realization of >10μm CW DFG in the BGSe crystal. We believe the developed dual-wavelength switchable and tunable RRFL can provide a new compact, robust, and cost-effective platform to realize broadly tunable light in both the visible and MIR regions, which can also find potential applications in imaging, sensing, and temporal ghost imaging in various spectral bands.

中红外(2.5 μm~25 μm)波段包含许多重要的原子和分子共振峰，因此中红外超连续谱广泛应用于生物医学、光谱学和环境科学等领域。碲化镉(cadmium telluride, CdTe)在中红外波段具有超宽的透射光谱范围0.86 μm~25 μm，同时CdTe具有较大的三阶非线性系数，是实现中红外超连续谱的理想材料。本文设计并加工了一种基于CdTe为芯层、低折射率介质硫化镉为缓冲层、硅为衬底的波导。采用广义非线性薛定谔方程仿真了该波导以中心波长为5.5 μm中红外激光作为泵浦，能够实现4.1 μm~9.7 μm的超连续谱输出。实验中通过湿法刻蚀制作CdTe多晶波导，并采用中心波长为1030 nm，脉冲宽度为250 fs的激光器作为泵浦源，观察到在波导中发生明显的自相位调制而产生的光谱展宽。该工作为CdTe集成波导应用于中红外超连续谱及中红外波段的片上光学器件提供了新的可能。