Transmission spectrum of Fabry-Perot interferometer based on photonic crystal

Abstract

A Fabry-Perot interferometer (FPI) constructed in a two-dimensional photonic crystal (2D PhC) has been proposed and demonstrated theoretically. The perfect 2D PhC consists of square-lattice cylindric air holes in silicon. Two same line defects with spacing of d = 16a , which is the physical length of the FP resonant cavity, are introduced in the PhC to form the FPI. The two line defects have high reflectivity and low transmission. Their transmission is between 4.81% and 11.1% for the self-collimated lights with frequencies from 0.275c/a to 0.295c/a and thus they form the two partial reflectors. Lights propagate in the FPI employing self-collimation effect. The transmission spectrum of the FPI has been investigated with the finite-difference time-domain method. The calculation results show that peaks have nearly equal frequency spacing 0.0078c/a . Even slight increases of d can cause peaks shift left to lower frequencies. As a result, the peak spacing decreases nonlinearly from 0.0142c/a to 0.0041c/a when d is increased from 9a to 30a . Through changing the configuration of the reflectors which results in transmission between 4.18% and 7.73%, the varieties of the sharpness of peaks and the degree of extinction of the frequencies between the peaks are obviously observed.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.