Tunable Demultiplexer Study in 2D Square Photonic Crystal

Abstract

We propose a novel designed structure which is a demultiplexer of 2D square photonic crystal of circular rods embedded in air that have locally three cavities with different sizes, refractive indexes, and also appropriately sized adjacent rods. Firstly, for one constant refractive index n (n = 3.3763) and with individual radius for each cavity and their adjacent rods, we have three different output resonant wavelengths; it means that this structure drops the desired wavelength depending on the geometric parameters. We have optimized this structure by varying locally the refractive index for each of the resonant cavity. In this case, we have obtained in one structure i.e. a single refractive index for all the structures except the cavities of course, three different zones with specific geometric and physical properties. As a result, three wavelengths have been extracted from these cavities. The corresponding optical transmission powers and Q factors are T1 = 83.54%, T2 = 100%, T3 = 81.97%, and Q1 = 2690.3, Q2 = 3248.8, Q3 = 8212.5, respectively. By changing both the size and refractive index of the cavity and the size of their adjacent rods, the structure is able to drop the desired wavelength, and the tunability property is achieved.