Micro-Compound Parabolic Concentrator (µCPC) arrays as an alternative to microlens arrays for avalanche photodiodes

Single photon counting sensors, such as avalanche photodiodes (APDs), require optical concentrators to compress incident light across a pixel down to the much smaller active area of each individual pixel. Traditionally, microlens arrays are used to focus the incident light onto the active area. However, these microlens array are limited in their acceptance cone, restricting the front-end optical systems to slower F/# systems. We propose micro-compound parabolic concentrators (μCPCs) similar to those used in solar arrays to enable the use of faster front-end optical systems for increased collection efficiency onto avalanche photo diodes. Due to their reflective design, μCPCs are wavelength agnostic and lend themselves to use in a wide variety of applications such as LIDAR and laser communications. Additionally, the accepted F/# is limited only by the detector active area and pixel pitch, making them ideal for fast, low SWaP systems.