为了得到角向偏振光输出,采用严格耦合波分析方法,设计了一种复合光栅镜.先通过对Ge光栅的伪博世工艺刻蚀特性的研究,得到了高深宽比的无定型Ge光栅.然后在栅槽底部引入了随机分布的Ge纳米针,在该光栅上依次镀金膜和介质保护膜,得到介质-金属复合光栅镜.最后将该复合光栅镜用作轴快流CO2激光器谐振腔尾镜,得550W角向偏振光输出.结果表明,纳米柱及金栅脊的引入使得该复合光栅镜具有很高的偏振选择性.

To achieve azimuthally polarized beam,hybrid grating mirror was designed based on rigorous coupled wave analysis method.At first,amorphous Ge grating with high depth-to-width ratio was obtained by studying the etching characteristics of pseudo Bosch process on Ge grating.And then,dielectric-metal hybrid grating mirror was obtained after the randomly distributed Ge nanoneedle was introduced at the bottom of gate groove,and gold film and dielectric protective film were coated in turn.Finally,550W azimuthally polarized beam was generated when hybrid grating mirror was used as the rear mirror of a fast axial flow CO2 laser.The results show that hybrid grating mirror has high polarization selectivity because of the introduction of nano-pillars as well as gold ridge.