Semiconductor photodetector array sensor integrated with optical-waveguide-based devices

Abstract

An optical signal to be detected enters single photon avalanche diode cells (SPAD) in a SPAD array and triggers photo event currents. Optical waveguides in the sensor carry an internal optical signal and a 1xN splitter divides the optical power into waveguide branchesN-. At the coupling structure, comprisingN-positive-intrinsic-negative diode photodetector/waveguide structures, photo event currents from SPAD cells are converted to a change in the internal optical signal, by modifying internal optical signalsN-. A waveguide combiner further integrates the modified internal optical signals resulting from the photo event currents from all the cells in the sub-array. After all waveguide branches' signals are combined, a photodetector detects the internal optical signal and outputs an electrical signal. The SPAD circuit may include additional capacitive coupling structures positioned between the SPAD cells and the photodetector/waveguide coupling structures.