一种条形亚波长径向偏振光栅

提出并设计了一种条形亚波长铝金属径向偏振光栅,用电子束直写方法制成,可以将偏振光偏振面的旋转直接转换为光斑的水平移动,通过定位光斑位移实现旋光角的测量.光栅由12000个单元水平排列组成,每个单元宽1μm,中心单元的格栅方向为0°,左右相邻单元的格栅分别按逆时针和顺时针方向依次旋转30″,最终实现±50°旋光角的测量范围.基于琼斯矩阵建立了光栅的理论模型,并运用严格耦合波理论分析了光栅的偏振特性与光栅脊厚、周期、占空比、入射光波长之间的关系,确定了光栅的最优结构.实验与仿真结果表明,光栅TM波的透过率大于80%、整体消光比大于26dB.这一测量模式不受光功率波动的影响,可以构成无机械旋转的新型旋光仪,或不需要旋转图像平移转换的电力光学传感器.

A Strip Sub-wavelength Radial Polarization Grating

A strip sub-wavelength radial polarization grating is designed in this paper.It is fabricated by beam direct write lithography,which can convert a rotation of polarization plane into the horizontal displacement of facula directly,so a linear measurement of rotation angle is achieved by locating the facula displacement.The grating consists of 12 000 units are arranged horizontally,the direction of the central unit is 0°,and the right or the left ones are rotated in turn by 30″in counterclockwise or clockwise directions respectively and finally achieve a measurement range of ±50°optical rotation angle.The theoretical model of the grating is established based on the Jones Matrix,and the relationship among the polarization characteristics and the grating ridge height,the period,the duty ratio,the incident light wavelength,the incident angle,and the temperature is analyzed by using the rigorous coupled-wave theory.The experimental and simulation results show that the grating TM wave transmittance is greater than 80%,and the extinction ratio is better than 26 dB.It achieves the optical power independent measurement of the optical rotation angle,which can be employed to build a new type of polarimeter with no mechanical rotating device or optical transducers with no rotary translation converter.