An optical analog-to-digital converter based on nonlinear resonant cavities in photonic crystals

In this paper, we present a new construction of an optical analog-to-digital converter in photonic crystals structure. The proposed structure consists of a Y-branch and three cavities based on nonlinear Kerr effect with different resonant modes in array of 37 × 19 dielectric rods. This effect allows resonant modes of cavities to be shifted to lower frequencies, which means their optical behavior depends on the intensities of optical input. One input and two output ports in a structure composed of silicon rods surrounded by air result in the desired binary output values. The normalized output power threshold for logic 0 and 1 are assumed 10% and 50%, respectively. The total footprint and the sampling rate for the proposed structure are approximately equal to 253 µm2 and 600 GS/s, respectively. This novel structure works in 1550 nm, and all the simulations and calculations are done based on finite-different time domain and plane wave expansion methods.