Reduction of afterpulse and dark count effects on SPAD detectors using processing methods

Abstract

Single-photon detector is a device that can detect fragile light signals such as photons. Noise is one of the major problems of Single-Photon Avalanche Diode (SPAD) in quantum communication and other applications. The two main noises in SPAD are afterpulse and dark count rate. Afterpulse is one of the most critical challenges of SPAD type InGaAs at 1550 nm wavelength. Several solutions have been presented to reduce noise. One of the most important methods presented is based on pulse gate. Pulse gate is effective in noise reduction by limiting SPAD operation time. Self-differentiating and up-conversion methods are also used in telecommunication wavelength SPADs to reduce noise, which have high implementation costs due to their complex structure. In this paper, we present a novel method for SPAD noise reduction. In this method, the time of SPAD output pulses is recorded and checked. The processor detects photon pulses and noise with a new algorithm. Noise pulses are removed, and photon pulses remain. This method is suitable for some Quantum Key Distribution (QKD) protocols that are simultaneous sender and receiver. It cannot be used in LiDAR and other similar asynchronous applications. The noise reduction method presented in this paper can be used for all types of single photon detectors and at different wavelengths. Also, this method can be used simultaneously with other noise reduction methods and it greatly reduces the amount of noise.

Keywords

• SPAD
• Detector
• Afterpulse
• Dark count
• QKD