High-performance binary blazed grating coupler used in silicon-based hybrid photodetector integration

An efficient and high-performance binary blazed grating coupler was designed based on silicon-on-insulator (SOI) used for silicon-based hybrid photodetector integration in an arrayed waveguide grating demodulation integrated microsystem. A relatively high coupling efficiency was obtained to optimize mode matching by the finite-difference time-domain method by choosing appropriate grating parameters, including period, etching depth, and fill factor. Coupling efficiency output at 1550 nm for the TE mode reached 68%. This value was >60% in the wavelength range of 1450 to 1600 nm, specifically 71.4% around 1478 nm. An InP/InGaAs photodetector and SOI wafer were integrated by using benzocyclobutene (BCB) bonding. When the thickness of the BCB bonding layer was 440 nm, power absorption efficiency at 1550 nm for the TE mode reached 78.5%, whereas efficiency reached similar to 81.8% around 1475 nm.