Pressure-dependent bandgap characteristics in photonic crystals with sensing applications

Abstract

The present study elucidates a photonic crystal (PhC)-based pressure sensor exploiting the change in refractive index with pressure and the corresponding structural deformation of the dielectric material. The stress-sensitive refractive indices of the constituent materials of the PhC have been considered to study the effect of applied pressure on the photonic bandgap (PBG) characteristics of the structure. The designed pressure sensor, proposed using a two-dimensional hexagonal lattice arrangement of air holes in a dielectric slab, operates in the high-pressure range of 1–6 GPa. A comparative study of the PBG characteristics with the application of high pressure has been reported for three semiconducting materials—GaAs, Ge and Si, used for the dielectric slab in the proposed structure. GaAs is found to exhibit the highest sensitivity to pressure variations and shows more pronounced shifting of the midgap wavelength with pressure in comparison to Ge and Si. The largest PBG is seen in the Ge-based structure, closely followed by the GaAs and Si-based structures. The proposed structure is suitable for high-pressure sensing applications.