液晶光学相控阵可编程光束偏转研究

Programmable Beam Steering Based on Liquid Crystal Optical Phased Array

研究了一种一维透射式向列相液晶光学相控阵.建立了器件的数学模型,根据Frank-Oseen液晶连续体弹性形变理论计算了电场作用下液晶指向矢分布,定量分析了器件的相位延迟及衍射特性.研制了含1024个驱动电极的实际器件,由FPGA对电极驱动电压进行可编程控制.经实验测试,该器件可以实现60个角度的准连续随机可编程电控偏转与扫描,最大偏转角度为2.0014°.根据器件的理论模型,对光束偏转的衍射效率进行了定性讨论,发现电极之间形成的"相位凹陷"是形成衍射旁瓣的直接原因.

A one-dimensional transmission-type liquid crystal optical phased array （LCOPA）was studied. Numerical model of the device was set up. The liquid crystal director distribution under electric field was calculated according to Frank-Oseen continuum elastic theory. The phase delay and diffraction characteristic of the device were quantitatively analyzed. A real device including 1 024 electrodes was developed,which was programmable driven by FPGA circuit. Experiment results show that 60 angles can be scanned by beam steering with quasi-continuous and random-access programmable way that controlled electronically,and the maximum deflection angle is 2. 001 4°. Based on the theoretical model of device,the diffraction efficiency of beam steering was discussed qualitatively. It shows that the phase valley produced between electrodes is the reason to form the diffraction lobes.