利用重复频率为25 MHz 的飞秒激光刻写铌酸锂掩埋式光波导,研究了在激光作用中心及热影响区域的物质结构,采用650 nm 的激光进行端面耦合实验,观测刻写区域波导的光传输特性及损耗测量.研究发现,在激光刻写区域的上下两个部位分别形成了传输损耗低于1.5 dB/cm 的单模光波导,而刻写区域中心未形成波导结构且光传输性能较弱.拉曼分析显示,刻写区域上下两个部位形成了致密化波导结构,而刻写中心形成了大尺度的缺陷.

A buried waveguide in LiNbO3 crystal is fabricated,by using the femtosecond laser which repetition rate is 25 MHz.The etching region can be divided into two regions which are inner interaction region and thermally modified region respectively.The coupling experiment shows two single mode buried waveguides are generated in the thermally modified region,and the propagation loss of the two waveguides are below 1.5 dB/cm.At the same time,the inner interaction region leading to a low transmittance.The Raman spectrum of the etching region is measured which shows the light-guide region is densificated by the thermal effect of high repetition,and there is a large-scale defects in the inner interaction region.