径向偏振光的退偏机理及补偿方法  

Depolarization mechanism and compensation scheme of radially polarized beams

作　　者：杨策 彭红攀 陈檬[1] 马宁 薛瑶瑶 杜鑫彪 张携 Yang Ce;Peng Hongpan;Chen Meng;Ma Ning;Xue Yaoyao;Du Xinbiao;Zhang Xie(Institute of Laser Engineering,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学激光工程研究院,北京100124

出　　处：《红外与激光工程》2021年第3期136-146,共11页Infrared and Laser Engineering

基　　金：国家自然科学基金(U1631240);北京市自然科学基金(KZ201510005001)。

摘　　要：研究了非均匀泵浦状态下径向偏振光束的退偏机理及补偿方法。理论分析表明,非均匀泵浦条件下各向同性晶体横截面内由热致剪应力引起的剪切向热致双折射是导致径向偏振光退偏的主要原因。设计实验依次采用薄膜偏振片(TFP)测量法和纯度测量法评价了径向偏振光在非均匀泵浦条件下的退偏,其中TFP测量法用于检测径向偏振光的整体退偏,纯度测量法用于检测径向偏振光的局部退偏。在泵浦峰值功率1.1 kW下,两种评价方法测得的退偏量分别为2.34%和2.53%。基于理论分析和评价方法的结果,在退偏补偿方案的设计中采用相位调制与空间模式匹配相结合的方法,将径向偏振光的退偏量优化了59%,并获得脉冲能量为19.36 mJ,纯度为90.13%的皮秒径向偏振光,光束质量因子M2为3.8。Depolarization mechanism and compensation scheme of radially polarized beams under non-uniform pumping were investigated.Theoretical analysis shows that,for the non-uniform pumping status,the thermal induced shear birefringence caused by the thermally induced shear stress within the cross-section of the isotropic crystal is the main reason for the depolarization of the radially polarized beams.Related experiments were designed to evaluate the depolarization of the radially polarized beams under non-uniform pumping conditions by using two methods of thin-film polarizer(TFP)measurement and purity measurement,in which the TFP measurement method was used to detect the overall depolarization of radially polarized beams and the purity measurement method was used to detect local depolarization of radially polarized beams.With a peak pump power of 1.1 kW,the depolarization measured by the two evaluation methods was 2.34%and 2.53%,respectively.Based on the theoretical analysis and evaluation results,a combination of phase modulation and spatial mode matching was considered in the design of the depolarization compensation scheme,which improved the depolarization of the radially polarized beams by 59%.Meanwhile,a picosecond radially polarized beam with a pulse energy of 19.36 mJ,a purity of 90.13%,and a beam quality M2 factor of 3.8 was achieved.

关 键 词：热退偏 径向偏振光 非均匀泵浦 退偏补偿 

分 类 号：TN248.1[电子电信—物理电子学]