Fringing-field minimization in liquid-crystal-based high-resolution switchable gratings

A liquid-crystal (LC)-based high-resolution switchable grating is proposed by using a double-sided structure, where striped electrodes are patterned on both sides of the LC cell. A unique biasing configuration is employed to successfully minimize the distortion of the LC director profile due to the fringing-field effects under two-dimensional electric fields. A first order diffraction angle of 14.5° with a diffraction efficiency of 33% for transmission light at 1.55 μ m is experimentally achieved. This result approaches the theoretical upper limit of 33.8% for a sinusoidal phase grating. The device efficiency is enhanced 80 times compared to a conventional single-sided device. Experimental results indicate the tolerance of electrode misalignment is 2 μ m .