Error performance optimization utilizing the dynamic detection cycle in a SPAD-based free space optical communication system.

Abstract

Afterpulsing is a critical non-ideal factor of the single photon avalanche diode (SPAD) at telecommunication wavelength, which limits the performance of a SPAD-based free space optical communication (FSO) system. Afterpulsing probability (AP) is highly dependent on the SPAD detection cycle. In a conventional SPAD-based system, the detection cycle is set to a relatively large constant time length to mitigate afterpulsing. However, it will limit the SPAD counting rate and degrade system performance. In order to improve system performance, a new scheme of the dynamic detection cycle is proposed to adapt to different operation conditions. Then, a multi-exponential model of AP is built and fitted with the test data of the single photon detector QCD-300. Furthermore, based on the joint model of the multi-exponential model of AP and bit error rate (BER) model of the SPAD-based FSO system, a simple and effective optimization algorithm is developed to optimize the detection cycle. And the optimization of the detection cycle under different operation conditions is also investigated. The results indicate that optimal detection cycle is dominated by signal light, background radiation, and SPAD gate length. Compared with a conventional scheme with a constant detection cycle, the proposed scheme with the dynamic detection cycle can improve system error performance effectively.