飞秒激光直写实现氧化锗玻璃内部光调制

Realization of Optical Modulation in Germanium Oxide Glass by Femtosecond Laser Direct Writing

利用脉宽和重复频率可调的超快激光系统,研究了氧化锗玻璃内部自组装纳米光栅的结构特点和关键影响因素。确定了氧化锗玻璃中纳米光栅的形成阈值,发现其与材料的带隙及激光的脉宽有关。在优化加工参数的基础上,利用纳米光栅的双折射特性,在氧化锗玻璃内部实现了光学微元件,并演示了其功能。分析了飞秒激光的重复频率对纳米光栅的形成和结构性能的影响,发现氧化锗玻璃中纳米光栅的双折射强度具有反常的偏振依赖性,并分析了这种现象出现的原因。

The structural characteristics and the key influencing factors of self-assembled nanogratings within GeO2 glass are investigated by using an ultrafast laser system with tunable repetition rate and pulse duration. The formation threshold of nanogratings in GeO2 glass is experimentally determined, which is dependent on material bandgap and laser pulse duration. In addition, based on the optimization of process parameters and the use of birefringence of nanogratings, the micro-optical components are fabricated within GeO2 glass and their functions are demonstrated. Moreover, the influence of repetition rate of femtosecond laser on the formation and structural properties of nanogratings is also analyzed. It is found that the birefringence strength of nanograting in GeO2 glass has an anomalous polarization dependence, and the corresponding origin is speculated.