Effects of hydrostatic pressure on the photonic band structure and quality factor of an L3 cavity in a photonic crystal slab

In this work, we investigate the effects of hydrostatic pressure on the photonic band structure and quality factor of the fundamental mode in an L3 cavity using the guided-mode expansion method in two-dimensional photonic crystal slabs. The two-dimensional photonic crystal is composed of air holes with circular cross-sections arranged in a hexagonal lattice. Here, the dielectric constant of the slab is a function of hydrostatic pressure and temperature. Upon increasing pressure at a given temperature, the photonic band structure exhibits a shift towards higher frequencies for the TE-like and TM-like modes of the photonic crystal slab. In the L3 cavity, the lateral displacement of the holes must also be considered as the quality factor of the fundamental mode increases with the displacement of the holes. However, there is evidence that the confinement of the L3 cavity decreases when both the hydrostatic pressure and the symmetric lateral shift of the holes increase.