Low power photonic devices based on electrically controlled nematic liquid crystals embedded in poly(dimethylsiloxane)

We present a new class of photonic devices in which light is confined in channel waveguides, named LC:PDMS, made of a nematic liquid crystal (LC) core in a poly(dimethylsiloxane) flexible substrates. Monte Carlo techniques have been used to study LC orientation. Homeotropic alignment of LC molecules has been observed without any applied electric field. A theoretical study of LC orientation under an electric field between coplanar gold electrodes deposited by electroplating has been carried. We report the design of two photonic devices based on LC:PDMS waveguide technology: a 2 × 2 optical switch made of a zero-gap electro-optical-controlled directional coupler and a multimodal interferometer (MMI) acting as an optical multi/demultiplexer. The electro-optical-controlled directional coupler is able to switch light from one waveguide to a second one with an extinction ratio of 16 dB with an applied voltage of just 1.62 V. Light remains in the same waveguide with an extinction ratio of about 18 dB with a voltage of 1.76 V. An MMI based on LC:PDMS technology has been designed to demultiplex wavelengths at 980 and 1550 nm in two output waveguides with an extinction ratio better than 11 dB by applying about 7 V.