Towards cavity-enhanced photodetection in Al-doped BP integrated with 2D photonic crystal and waveguide for mid-IR wavelengths

The design of an integrated Al-doped BP p-n homojunction with 2D Photonic crystal coupled with strip waveguide in SOI to enhance Photodetection for 3.7 μm is presented. Peak-Q of 1600 has been achieved by systematically optimizing the radius of the circularly shaped unit cell and period by performing 3D FDTD simulations. The thickness of the BP layer is calculated to be 17 nm for 3.7 μm absorption. The energy band structure and density-of-states for the monolayers are calculated using quantum expresso. The available 400 nm thick SOI lithography, in a standard multiproject wafer run, can be employed to ac hive the monolithic integration of our designed photodetector for mid-IR wavelengths. We believe this platform could help in realization of chip scale system for sensing application, optical wireless applications, interconnects (on-chip optical) and phased array for LIDAR applications.