TUNABLE 1D PHOTONIC CRYSTAL STRUCTURE BASED ON GROOVED Si INFILTRATED WITH LIQUID CRYSTAL E7

Abstract

Tuning of a photonic band gap (PBG) in a composite one-dimensional photonic crystal infiltrated with nematic liquid crystal (LC) E7 has been evaluated by simulations. It has been found that a sufficient shift of the short wave edge can be obtained only in structures with a pronounced initial alignment of a LC director in the grooves of a single crystalline Si matrix. The largest effect Δλedge = 0.52 μm is predicted for the reorientation of LC molecules from planar homogeneous alignment along the grooves to homeotropic alignment with respect to the Si walls due to an electro-optical effect. The shift in PBG due to thermal tuning resulting from the transition of LC from mesophase to the isotropic phase (Δλedge = 0.4 μm) is less than that due to electric tuning. Thermo-tuning has been demonstrated experimentally, and PBG shift as high as Δλedge = 0.25 μm has been achieved.