Tunable optical properties of silicon-on-insulator photonic crystal slab structures

A photonic crystal slab structure with one-dimensional periodicity, obtained by preferential etching of a silicon-on-insulator wafer, is numerically investigated in 3-D. The etched grooves are considered to be filled either with an isotropic or with a Nematic Liquid Crystal (NLC) material. The molecular director is calculated using a consistent model of NLC reorientation under an external voltage. Different structures together with a broad range of voltage values are numerically simulated by means of a three-dimensional finite-difference time-domain method. The shifting of the photonic bandgap induced by the applied voltage, as well as its sensitivity in terms of refractometric applications, are discussed for a range of different structure geometries.