We demonstrate single-mode microdisk lasers in the telecom band with ultralow thresholds on erbium-ytterbium co-doped thin-film lithium niobate (TFLN). The active microdisk was fabricated with high-Q factors by photolithography-assisted chemomechanical etching. Thanks to the erbium-ytterbium co-doping providing high optical gain, the ultralow loss nanostructuring, and the excitation of high-Q coherent polygon modes, which suppresses multimode lasing and allows high spatial mode overlap between pump and lasing modes, single-mode laser emission operating at 1530 nm wavelength was observed with an ultralow threshold, under a 980-nm-band optical pump. The threshold was measured as low as 1 µW, which is one order of magnitude smaller than the best results previously reported in single-mode active TFLN microlasers. The conversion efficiency reaches 4.06 × 10^-3, which is also the highest value reported in single-mode active TFLN microlasers.

为了在设计阶段预测光学系统加工装配后的像质并降低加工装配难度，提升设计效率，文中提供了一个高效的公差灵敏度降低方法。首先使用Zernike多项式量化像差，基于线性代数理论和Monte Carlo分析寻找引入扰动后系统的像差变化规律，通过降维后的像差场以及特征值分布确定主要引入像差；对系统制造过程中可能出现的失对称扰动和轴向扰动进行建模，基于节点像差理论描述扰动造成的引入像差，并通过统计分析确定关键表面；根据Zernike项与波像差的对应关系对像差空间进行变换，提出相应的评价函数纳入优化，进而抑制新像差的产生。将这一方法应用于两个不同的光学系统的设计，优化后预期加工性能（指定空间频率处98%置信度的MTF表现）分别提升了约68%和20%。与使用Zemax软件中TOLR操作数优化相比，结构1的优化时间由7 h缩短到36 min，并且在结构2的优化中成功实现了公差降敏。结果表明，该方法能够在提升效率的同时有效降低公差灵敏度。

由于空间光环境的复杂性，抑制杂散光对保证空间相机成像性能尤其重要，该文针对宽光谱波段成像的空间探测相机光学系统进行杂散光分析和抑制优化设计。通过SOLIDWORKS和TracePro的无损式数据交互建立光机模型，并从光机材料的表面特性、机械结构、镜片透过率等多角度优化杂散光模型，再利用朗伯体光源分别对正反向进行光线追迹，然后结合光机模型的半剖图对系统关键表面进行重点取样分析。分析结果表明：优化后的光机系统在离轴角10.3°~15.4°内，点源透过率值与优化前的系统相比下降了66%~99.4%，在离轴角大于14.2°时点源透过率值接近10^?4量级，在离轴角18.4°处杂散光的点源透过率约为10^?4量级。最后通过鬼像实验，进一步证明了优化后的光机系统设计方法具有良好的杂散光抑制效果。