Optimization and realization all-optical compact five-channel demultiplexer using 2D photonic crystal based hexagonal cavities

In this paper, a compact all-optical five-channel demultiplexer (DEMUX) using 2D photonic crystal hexagonal cavities is proposed. The proposed DEMUX comprises bus/drop waveguides, photonic crystal waveguides containing four consecutive 120° bends, two power splitters, and hexagonal resonant cavities. By adjusting the radius and refractive index of the inner/coupling rods, position, and radius of the scattering rods, the operating wavelength and the output power of each port are managed. Normalized transmission spectra and calculations of band structure are calculated by the finite-difference time-domain (FDTD) and plane-wave expansion (PWE) methods, respectively. The resonant wavelengths of the proposed structure are 1328.7 nm, 1331.9 nm, 1335.4 nm, 1340.5 nm, and 1344.4 nm, respectively. Calculation results show that the average quality factor, optical transmission efficiency, passbands of channels, minimum and maximum crosstalk of nearly 6236, 95.98%, 0.22 nm, − 18.04 dB, and − 50.2 dB, respectively. The operating wavelength range of DEMUX is 1328 nm to 1345 nm and the average channel spacing between the channels nearly about 3.93 nm. The footprint of the device is 240 μm2. The advantageous features of the proposed structure are valuable for integration based on popular planar technology and optical communications systems.