InGaAs avalanche photodiodes (APDs) are convenient for single photon detection in the near infrared (NIR) including the fiber communication bands . However, to suppress afterpulse noise due to trapped avalanche charge, they must be gated with megahertz repetition frequencies, thereby severely limiting the count rate in NIR applications. Here, the authors show gating frequencies for InGaAs APDs well beyond . Using a self-differencing technique to sense much weaker avalanches, the authors reduce drastically afterpulse noise. At , they obtain a detection efficiency of 10.8% with an afterpulse probability of 6.16%. In addition, the detector features low jitter and a count rate of .
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No maximum count rate of PPLN upconversion detectors has been reported, and the value here is inferred from the performance of Si-APD single photon detectors (see: Datasheet SPCM-AQR Single Photon Counting Module, Perkin-Elmer).
