摘要
经过铌酸锂晶体倍频后的输出光,其各向异性因离散角较小,在较短的晶体中两个偏振光并不完全分离,所以仍然存在偏振态问题。从晶体的主轴坐标系出发,得到了任意通光方向的铌酸锂晶体(LN)的二阶非线性电极化系数矩阵和倍频光偏振态的表达式。对1064 nm基频o光产生的倍频光偏振态进行了仿真计算,结果表明:在庞加莱球上,波矢与光轴的夹角γ保持不变而改变波矢方位角θ时,倍频光偏振态将随波矢方位角θ变化而在S_(2)S_(3)平面上旋转,其旋转轴由夹角γ所决定,但旋转角呈现非线性变化且与起点有关。倍频光偏振态对夹角γ敏感,保持θ不变而改变γ时偏振态呈现与θ取值有关的周期性变化。该理论研究成果可为全面研究倍频偏振光的偏振特性及应用提供理论依据。
In the shorter lithium niobate(LN)crystal,the two polarised lights of the frequency-doubled are not entirely separated due to the small anisotropy and slight walk-off angle.There is still a polarization state(SOP)problem.In this paper,the SOP of second harmonic(SH)light in this crystal has been comprehensively studied.Starting from the principal axis coordinate system of the crystal,the second-order susceptibility matrix and the expression of SOP of the SH light in the LN crystal in an arbitrary direction of light propagation are obtained.The SOP of the SH light generated by the 1064 nm fundamental polarised in the o direction is calculated.The results show that when the angleγbetween the wave vector and the optical axis is fixed and the azimuthθof the wave vector is changed,the polarization state of the SH light will rotate withθaround the rotation axis determined by the angleγon the S_(2)S_(3)plane,the rotation angle is non-linear and related to the starting point.The polarization state of the SH light is sensitive to the angleγ,and the change of the polarisation state of the SH light with the change ofγwhile keepingθunchanged shows a periodic change related to the valueθ.The results can provide a theoretical basis for a comprehensive study of the polarization characteristics and probability of applications of frequency-doubled polarisation light correct.
作者
刘栋
刘岚岚
吴重庆
程前
王健
LIU Dong;LIU Lanlan;WU Chongqing;CHEN Qian;WANG Jian(Institute of Optical Information,Key Laboratory of Luminescence and Optical Informatior,Ministry of Education,Beijing Jiaotong University,Beijing 100044,China)
出处
《激光杂志》
CAS
北大核心
2021年第5期15-21,共7页
Laser Journal
基金
国家自然科学基金项目(No.61775012)。
关键词
二次谐波产生
双折射
偏振态
铌酸锂晶体
second harmonic generation
birefringence
state of polarisation
lithium niobate crystal
