Study of two dimensional photonic crystal nanocavities based on Gallium Nitride (GaN)

In this work, we shed light on a theoretical study of photonic crystal (PhC) cavities on Gallium Nitride (GaN). Particularly, the photonic band gap (PBG), resonant wavelength and quality factor (Q) of designed PhC structures were studied. In fact, the PBG was calculated by the plane wave expansion (PWE) method and the normalized transmission spectra of suspended GaN-based PhC cavities were obtained using finite difference time domain (FDTD) method. Accordingly, the resonant mode of GaN-based PhC cavity was observed at ∼460 nm wavelength. Furthermore, the optical confinement of the hexagonal cavity can be improved by adjusting the diameter and the distances of the adjacent holes along with the change of the cavity's type from the H0 to the L3. Indeed, the transmission spectrum of the cavity was found to be strongly modified by the increase in the size of the structure, in the shifted distance value and the number of the shifted holes as well as the decrease of the holes diameters surrounding the defect in addition with changing the type of the cavity in order to obtain a significantly narrow FWHM of 0.002 pm. To sum up, our simulation results were in accord with those obtained from OptiFDTD software.