Optical four-channel demultiplexer based on air-bridge structure and graphite-type ring resonators

A novel an optical four-channel demultiplexer based on a hexagonal lattice shape of embedded air holes in dielectric substrate (air-bridge type) is proposed. Demultiplexing for each channel is obtained by designing the graphite-type ring resonator which consists of small air hole defects in own unit cells. The physical parameters which govern the demultiplexer performance are investigated. It is observed that employing big air hole as a defect in the end of input waveguide enhanced the coupling efficiency between the rings and waveguides. By engineering the refractive index of substrate and size of air holes, the proposed demultiplexer is tuned. The demultiplexer has an average quality factor > 3000 and channel spacing Δ λ ≤ 2 nm . We showed that big air hole defect in the end of input waveguide is an effective scheme for improving the transmission efficiency and cross talk between channels. The average transmission efficiency and cross talk value are above 98% and − 23 dB, respectively. The total size of proposed structure and its maximum delay time are 289 μm 2 and 0.3 ps, respectively. Our demultiplexer has an easy fabrication structure, and it can find key applications for many cores CPU in an on-chip optical network and the dense wavelength demultiplexing in optical integrated circuits.