Room temperature continuous frequency tuning InGaAs/InP single-photon detector

The available high speed InGaAs/InP-based single-photon avalanche detectors (SPAD) are normally worked at fixed gate or narrow tunable gate frequency. However, a wide tunable gate frequency or even free running single photon detectors at high speed would be very useful in quantum key distribution, quantum entanglement distribution and so on. Here, we present a high speed InGaAs/InP-based single photon avalanche detector (SPAD) with tunable gate frequency from 900MHz to 1000MHz which also can work under the room temperature without any cooling setups. Instead of restricting the spike noise by self-differencing or filtering method, we use an Analog to Digital Converter(ADC) to sample the output voltage of the APD. Through the sampled voltage we can discriminate an avalanche signal from the noise. Based on the sampling method, a room temperature SPAD is implemented with a dark count rate of 2.5 × 10−5 per gate and afterpulse probability of 1.3%, given the condition that detection efficiency of 10.6%, dead time of 1ns, and clock frequency of 1GHz. The wide tunable gate frequency makes the SPAD very suitable for practical use and commercial producing.