| The technology of single photon detection is crucial to realize the high-precisionmeasurement and new communication system. Avalanche photodiode (APD), with theadvantages of small-scale, low operating voltage and high sensitivity, has been widelyemployed in the field of single photon detection. With the favourable response totelecom-band photons, the InGaAs/InP APD is always operated at gated Geiger modeto suppress the dark counts and after pulses. In the single photon detection systemdesign, it is a challenge to extract the weak photon induced avalanche current from thecharge and discharge pulses, which are attributable to high-speed gate pulses actingon the junction capacitance.With the InGaAs/Inp APD, the gated Geiger mode single-photon detectionsystem is established in our paper. When the avalanche signal and discharge pulse areproperly overlapped in time domain, the photon signal can be discriminated byhigh-speed comparator. The experiments results of10%quantum efficiency and1×10-2/pulse dark count probability are obtained in the room temperature, when theincident light intensity is fixed at0.1photon/pulse. The scheme is easy to operationand stable working. In addition, dark count probability can be reduced by cooling theAPD. The main contents of the paper are as follows:1. The devices and methods applied in telecom-band photon detection areintroduced.2. Several typical methods of extracting the weak avalanche signal from spikenoise are presented.3. After measuring the operating parameters of the APD, the single-photondetection system is built up based on negetive pulses comparating method. Thesystem is highly sensitive to the avalanche signal, which is benficial to reduce thedark count probability and supress the after pulses.4. In the room temperature, the reponse time, quantum efficiency and dark countprobability of detection system are measured. In conclusion, the method ofdiscriminating the negative pulses can be used to single photon detection systems. |
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