飞秒激光刻写铌酸锂光波导的实验研究

Experimental Research on Congruent LiNbO_3 Waveguide Fabricated by Femtosecond Laser Pulses

研究了飞秒激光加工参量对刻写质量的影响,分析了激光能量吸收的多光子效应,测试了刻写通道的传输特性.实验结果表明,激光刻写的通道具有良好的波导特性:当激光脉冲能量在20μJ左右,扫描速度在300μm/s～400μm/s之间时,刻写通道的传输损耗小于1dB/cm,低于晶体的传输损耗,其原因是激光诱导锂离子的扩散引起了晶体内部局部折射率的增加.

The experimental research of optical channel waveguides in congruent LiNbO3 crystals using femtosecond pulses was performed on Ti：sapphire laser system. The effect of fabrication parameters such as laser scanning speed and pulse energy on writing quality was studied. Relative microstructures were obtained respectively,and their characters were analyzed in detail. The 1 550 nm band fiber loop laser was set up to measure propagation loss. The result shows that channels propagation loss in channel, which were processed under 20/μJ pulse energy and scanning speed between 300 /μm/s and 400 /μm/s, was lower than LiNbO3 crystal. It is demonstrated that the channel acts as a waveguide,and the propagation loss was lower than 1dB/cm.