Low-Power All-Optical Bistable Device of Twisted-Nematic Liquid Crystal Based on Surface Plasmons in a Metal--Insulator--Metal Structure

A low-power all-optical bistable device of twisted-nematic liquid crystal (TN-LC) is reported, on the basis of coupled surface plasmons (SPs) in a metal--insulator--metal (MIM) structure. The lowest threshold switching illumination was 0.3 mW/mm 2 , which is much lower than the value we previously reported for a similar all-optical TN-LC device based on the coupled SPs in a gold grating. The threshold illumination is lower at higher temperature up to the phase transition. The TN-LC device is promising for two-dimensional optical memories or spatial light modulators, since the structure is simple and free from electronic circuits.