Hybrid wavelength-polarization-division demultiplexer based on honeycomb-lattice photonic crystal structures on a...

This paper presents a hybrid wavelength-division multiplexing (WDM) and polarization-division demultiplexing (PDM) device using silicon rods in the honeycomb-lattice photonic crystal structure. The device consists of a directional coupler to split the TE and TM polarizations and channel drop filters that drop the resonant channel wavelengths for both polarizations. The coupling length of the directional coupler is optimized such that only TE-polarized light is coupled to the waveguide, which is placed parallel to the input waveguide, thus separating it from the TM-polarized light. The parameters of the nanocavities in the channel drop filters are optimized to achieve resonant wavelengths in the C-band wavelength range. The period of the rods in the y direction (a_yn) is discretely chirped within each cavity channel section to minimize losses and improve efficiency. The proposed WDM -PDM device has been simulated using the finite-difference time-domain (FDTD) solver, achieving a minimum insertion loss and a linewidth of 0.50 dB and 1.60 nm, respectively. The footprint of the proposed device is 37.00µm×44.63µm. The fabrication tolerance study for over-etch and under-etch conditions is performed, and the rate of the resonance wavelength shift of <2.65 is achieved.