Challenges of developing resonant cavity photon-counting detectors at 1064 nm

Abstract

Deep Space Optical Communications (DSOC)) impose challenging requirements on detector sensitivity and bandwidth [1]. The current state-of-the art of high-repetition rate, high-power lasers recommends using near-infrared (NIR) 1064nm wavelengths for specific DSOC tasks [2]. Large photonic arrays with integrated beam acquisition, tracking and/or communication capabilities, and smart pixel architecture should allow the implementation of more reliable and robust DSOC systems. Integration of smart pixel technology for parallel data read, acquisition and processing is currently available in silicon. Therefore it would be desirable to monolithically integrate the photodetectors with the electronics. However, silicon has a weak absorption at 1064nm. One elegant approach to increase its absorption efficiency is to trap the photons inside the silicon using the cavity resonance effect (resonant cavity enhancement or RCE). We present in this paper the challenges of developing resonant cavity single-photon detector arrays for applications to DSOC. The metrics of the main process parameters to fabricate resonant cavity detectors is analyzed and critical process steps are developed and evaluated. We conclude that such detector arrays are feasible using current state-of-the-art CMOS technology, provided that suitable process control protocols are developed. We report a 10X performance enhancement at NIR wavelengths for the first generation of resonant cavity single-photon detector prototypes, less than 150ps timing performance in photonstarved mode and 20-30ps for multi-photon hits.