Direct investigation and accurate control of phase profile in liquid-crystal optical-phased array for beam steering

An experimental setup and simple method were proposed to investigate and control the actual phase profile in a high-spatial-resolution liquid-crystal optical-phased array (LCOPA). A crossed polarizer and high-resolution microscope objective were employed to transform the light distribution out of the liquid-crystal layer into a polarization-interference pattern in which the phase-profile information was wrapped. The polarization-interference pattern was then directly translated into the actual phase profile. Based on this setup, a method was developed to accurately control the actual phase profile, and the steering efficiency at the steering angle of 16 mrad was increased from 80% to 90%. The proposed method also helps in increasing the steering efficiency when disclination lines appear.