Nonlinear dielectric optomechanical metamaterials

Abstract

We introduce a dielectric photonic metamaterial presenting a giant nonlinear optical response driven by resonant optomechanical forces. Being inherently free of Joule losses, it exhibits optical bistability at intensity levels of less than 0.2 mW μm−2 and, furthermore, manifests nonlinear asymmetric transmission with a forward∶backward optical extinction ratio of more than 30 dB. Scientists have designed a metamaterial whose optical properties can be switched/tuned using optomechanical forces. The structure comprises an array of nanoscale silicon blocks with alternating thickness that are supported by a series of parallel flexible silicon nitride beams. Incident infrared light generates optomechanical forces that cause the beams to be displaced, thereby modifying the structure’s optical properties. The resulting material thus exhibits strongly nonlinear and asymmetric transmission as a function of input optical power, as well as bistable behaviour. Jianfa Zhang and colleagues from the University of Southampton, UK, and Nanyang Technological University, Singapore, report that optical intensities below 0.2 mW per square micron are sufficient to induce dramatic changes in transmission at telecommunications wavelengths around 1,550 nm.