Performance of new InGaAs/InP Single-Photon Detectors for the Near-Infrared Spectral Range

New InGaAs/InP Single-Photon Avalanche Diodes (SPADs) offer remarkable performance and dedicated electronics makes possible to fully exploit it. They are of the utmost interest for counting and timing single-photons in the near-infrared range (800nm < λ < 1700 nm), as required by Quantum Key Distribution (QKD) for secure communications and LIDAR and LADAR in eye-safe mode. Experimental characterization demonstrated that they provide good photon detection efficiency (> 25%) and fairly low noise (dark-count rate <10 kcps) at moderate cooling (> 225 K). Studies on primary dark counts have been carried out at various temperatures for assessing the roles of thermal generation and trap-assisted tunnelling in the detector noise. The effectiveness of trapping levels as a function of their location within the electric field distribution has been studied in order to gain a better understanding of the afterpulsing effect and quantitative data are obtained by computer simulation. Custom fast electronics has been developed for operation in gated-mode with subnanosecond gate transitions and time-jitter better than 50 picoseconds has been verified in single-photon timing.