基于低散射和高增益全息液晶/聚合物光栅的分布反馈式激光器

摘要

In this paper, we utilize the acrylate monomer of low functionality to fabricate a holographic polymer dispersed liquid crystal grating with polymer-scaffolding morphology. It is effective to reduce the scattering loss in the grating which acts as a resonator in distributed-feedback laser since there is no droplet of liquid crystal. Moreover, the use of the monomer with high refractive index (RI) ensures the formation of grating with high RI modulation and, correspondingly, high feedback gain. For these two factors mentioned above, an excellent laser property is obtained from the dye-doped laser pumped by Nd:YAG pulse laser at 532 nm. A spectral linewidth of 0.3 nm is observed at pump energy threshold 0.8 µJ/pulse and a conversion efficiency of 1.2%is achieved at operating wavelength 635 nm. The laser performance is improved in some aspects such as threshold energy, linewidth and conversion efficiency to some extent compared with those reports proeviously.%　　利用低官能度的丙烯酸酯单体进行全息液晶/聚合物光栅的制备,获得了具有聚合物支撑形貌的光栅结构.由于这种光栅内部不存在液晶微滴,当作为分布反馈式激光器的谐振腔时,可以有效降低光栅内部的散射损失(<4%),降低激光腔损耗.此外,选用的高折射率单体提升了光栅的折射率调制量,增强了光栅的反馈增益.在以上两种因素的共同作用下,采用染料DCM为激光工作物质,以532 nm的Nd：YAG脉冲激光器作为抽运光源,最终获得了中心波长为635 nm,转化效率为1.2%的高性能激光,在以阈值能量0.8µJ/pulse抽运下获得激光线宽0.3 nm,较之国内外同类激光器的报道,在阈值、线宽、转化效率三方面均有不同程度提升.