LOW VOLTAGE AVALANCHE PHOTODIODE WITH RE-ENTRANT MIRROR FOR SILICON BASED PHOTONIC INTEGRATED CIRCUITS

摘要

A low voltage APD disposed at the end of a waveguide extending horizontally in a silicon device layer of a PIC chip is disclosed. The APD is disposed above the inverted concave mirror co-located at the end of the waveguide to connect the light by internal reflection down the APD from the waveguide. In an exemplary embodiment, a 45 ° -55 ° facet is formed in the silicon device layer by crystallographic etching. In an embodiment, the APD comprises a silicon-increasing layer, a germanium adsorption layer on the increasing layer, and a plurality of ohmic contacts disposed on the adsorption layer. The underlying optical reflective metal film interconnects a plurality of ohmic contacts and returns the transmitted light around the ohmic contact to the adsorbent layer for greater detector responsiveness.