InGaAs/InAlAs avalanche photodetectors integrated on silicon-on-insulator waveguide circuits

We simulated an evanescently coupled InGaAs/InAlAs avalanche photodetector integrated on silicon-on-insulator waveguide circuits using benzocyclobutene as the bonding layer. A silicon fiber-grating coupler is adopted to couple light from the fiber to the Si waveguide, and light is ultimately absorbed in the absorption region. Simulations aimed at improving the optical coupling efficiency using different device dimensions such as different benzocyclobutene bonding thicknesses, different InP layer parameters and different silicon waveguide widths were carried out. The simulation result shows a detection efficiency of 96.7% for a 2 pm silicon waveguide device with a photodetector length of 40 pm, which can obtain a gain-bandwidth product of 135 GHz at 1550 nm.