除了激光源、偏振分光镜（PBS）和波片等偏振器件之外，非偏振分光镜（NPBS）也是外差干涉仪中重要的非线性误差源。研究了多层介质膜NPBS的退偏效应和方位角对非线性误差的影响。采用p、s分量透射比、反射比、反射相移和透射相移共同表征NPBS的退偏效应，并逐项分析了其非线性误差模型。如果入射光束为理想线偏振光，则只有NPBS的反射相移和透射相移影响测量精度。如果入射光束存在偏振椭圆化和非正交，则NPBS的方位角、透射比和反射比、相移等参数的变化都会引入非线性误差，误差曲线的斜率受椭圆率和非正交角的影响。因此选用不同的激光源，同一个NPBS产生的非线性误差大小不同，一般可达几个纳米量级。为了实现纳米/亚纳米级精度的外差干涉测量，选择性能稳定的NPBS，特别是NPBS退偏效应与激光源输出偏振态之间的匹配非常重要。

Continuous-wave green laser with a maximum power of 34 W has been obtained by intracavity frequency doubling with KTP in diode-side-pumped Nd:YAG. The Nd:YAG/KTP green laser has a simple three-mirror V-fold cavity structure. The optical-to-optical conversion efficiency is 9.5%. The instability of the laser is measured when the output powers are near 16, 21, 30, and 34 W after the beam is filtered. At the maximum output power, the M<sup>2</sup> factor is measured to be 8.

基于带有各向异性完全匹配层吸收边界条件的紧凑二维频域有限差分法(2D-FDFD)对八角格子光子晶体光纤(O-PCF)的模式分布、模式截止特性以及色散特性进行了数值模拟。通过计算八角格子光子晶体光纤前20个模式分布发现,其模场形状比六角格子光子晶体光纤(H-PCF)的好,更接近于圆形; 利用有效面积方法分析了八角格子和六角格子光子晶体光纤基模和二阶模的截止特性,得到了非限制模、基模和多模的相图。比较发现相同填充率和空气孔间距时,八角格子光子晶体光纤的单模运转区域要比六角格子光子晶体光纤的宽,且更易用于色散补偿。

A widely and continuously tunable optical parametric generator (OPG) pumped by a 1064-nm acousto-optically Q-switched diode-end-pumped Nd:YAG laser based on MgO-doped periodically poled LiNbO3 crystal with a multigrating structure (29.2-30.4 micron) is reported. A broad continuous signal spectrum of 1513-1700 nm is obtained by changing the crystal grating periods from 29.2 to 30.4 micron and by tuning the crystal temperature from 30 to 180 Celsius degrees simultaneously. When the average pump power is 1.82 W with pulse duration of about 70 ns operating at a repetition rate of 10 kHz, the maximum signal output power of the periodically poled MgO-doped lithium niobate (PPMgLN) OPG is about 210 mW corresponding to the idler and total powers of 118.4 and 328.4 mW respectively.