design and simulation of an eight-channel demultiplexer based on photonic-crystal ring resonators

In the present study, an eight-channel photonic crystal wavelength demultiplexer is designed for separating eight telecommunication wavelengths: λ₁=1.5552 nm, λ₂=1.5563 nm, λ₃ =1.5579 nm, λ₄=1.5593 nm, λ₅ =1.5608 nm, λ₆ =1.5623 nm, λ₇ =1.5638 nm, and λ₈ =1.5653 nm. to this end, a two-dimensional photonic crystal structure composed of circular silicon rods arranged in an air background and fabricated on a silica (sio₂) substrate is employed.the design and analysis are performed using the plane wave expansion (pwe) method to compute the photonic band structure and guided modes, while the finite-difference time-domain (fdtd) method is used to calculate transmission efficiency and analyze propagation characteristics during wavelength-selective separation. ultimately, by optimizing the resonator placement and the radius of point defects, a channel spacing of 1.44 nm and a transmission efficiency (te) of 93% were achieved.