Width-modulated tapered air-slot based photonic crystal nanocavity

A width-modulated air-slot photonic crystal (PhC) nanocavity is designed and analyzed. A tapered air-slot, instead of a regularly arranged rectangular slot, is used at the center of a W1 PhC waveguide. This is to reduce the vertical radiation loss which occurs at the abrupt termination of a rectangular slot, and also to increase the inline coupling from a waveguide to the cavity. A three dimensional finite difference time domain method is used to calculate the resonant wavelength, quality factor and modal volume of the cavity which are found as 1.559 μm, 3.4×10 6 and 0.154 μm 3 respectively.