Design and optimization of four channel Dense Wavelength Division Multiplexing demultiplexer using photonic crystals square resonant cavity

摘要

A four-channel Dense Wavelength Division Multiplexing (DWDM) demultiplexer is proposed and designed using a two-dimensional photonic crystal square lattice in order to precisely confine the light in horizontal direction. The proposed demultiplexer comprises a T-shaped bus waveguide, four drop waveguides and four square resonant cavities. The T-shaped waveguide is designed with line defects, and wavelength selective filter is realized using square resonant cavity. The square resonant cavity designs with inner ring filter rods, outer ring rods, and resonant rods. The desired wavelength can be separate by adjusting the inner ring filter rod radius and resonant rod. The proposed PC based demultiplexer can drop four different wavelengths (1555 nm to 1558 nm) with 1 nm of uniform channel spacing, which is promptly suitable for DWDM applications. The channel bandwidth, transmission efficiency, crosstalk, and Q factor of the proposed device is about 0.2 nm, 99-100 %, - 40 dB and 7775-8000, respectively. The simulation is carried out with Two-Dimensional Finite Difference Time Domain (2D-FDTD) technique and Plane Wave Expansion (PWE) method with perfectly matched layers (PML) absorbing boundary conditions (ABC). The size of the proposed device is 447 mu m(2) hence it could be implemented for Photonic Integrated Circuits (PICs).