Performance study on an open photonic crystal cavity

To study the property of an open photonic crystal cavity, the new open cavity, formed by 30 vertex angle of the photonic crystal and air tank alternately was analyzed based on the plane wave expansion method and finite-difference time-domain method. It was found that the open cavity structure had negative refraction property in both the normalized frequency bands (0.3006~0.35 and 0.6755~0.6851), and a zero-optical path closed-loop could be formed with the air tank in the frequency range of negative refraction; and there was a high transmission rate in the photonic crystal and air tank boundaries, so resonance could happen at a certain wavelength. The results indicate that the refractive index can be measured with high sensitivity using this open photonic crystal cavity whose resonance wavelength varies with the refractive index.