A new proposal for a high-performance 4-channel demultiplexer based on 2D photonic crystal using three cascaded ring resonators for applications in advanced optical systems

In this paper, a high-performance 4-channel demultiplexer (DEMUX) based on 2D photonic crystal using three cascaded ring resonators is proposed. The proposed DEMUX is composed of square lattice of silicon dielectric rods with a refractive index of 3.46 suspended in air. For the proposed device, the lattice constant a = 590 nm and the filling factor r/a = 0.2. In this study, the plane wave expansion and finite-difference time-domain methods are used respectively to characterize the photonic band gap and to investigate the optical behaviour of the structure. It is demonstrated that by choosing appropriate values for the radius of the inner rods, scattering rods, coupling rods and the coupling length between the bus and the drop waveguides, the desired wavelengths can effectively be separated. The resonant wavelengths of the proposed DEMUX are 1528.7 nm, 1535.3 nm, 1531 nm, and 1533 nm. The mean quality factor, spectral bandwidth and the transmission efficiency of our device are computed to be respectively 7358.5, 0.217 nm and 99.25%. The proposed DEMUX has a mean channel spacing, minimum and maximum values of crosstalk of about 2.2 nm, - 46.68 dB and - 9.79 dB, respectively. Furthermore, the footprint of the device is 294.4 mu m(2), which is suitable for photonic integrated circuits.