Design Of High-Speed Single-Photon Detector Using InGaAs Avalanche Photodiode

In the last decade, more and more quantum information applications such as quantum key distribution have been extensively demonstrated. Especially, quantum communication performs quantum key distribution (QKD) based on quantum mechanics for safe key exchange. It provides an ideal solution for traditional cryptography key exchange.1310nm,1550nm, which have the least loss of optical fiber, is the main quantum communication band. It is greatly significant to develop stable and efficient infrared single-photon detectors because the infrared photon signal is too weak to detect.Among the detection techniques of all wave bands, near infrared single-photon detection technique attracts more attention for its application significance. Especially in the quantum key distribution system, near-infrared single photon detector in the communication wavelength window have a great effect on the communication distance, quantum key generation rates and quantum bits error rates of the system. And near-infrared single photon detector also has great applications in the laser ranging, ultrasensitive infrared spectrum area. Therefore, how to increase the repetition frequency, detection efficiency and S/N is the target of this thesis.In the thesis, single-photon detector at1550nm with a high repetition frequency up to200MHz is realized using an InGaAs/InP avalanche photodiode operated with a sine wave gating. Avalanche photodiodes (APDs) in Geiger mode have been widely used for the SPD. However, the APD in Geiger mode is very noisy, resulting from the afterpulse and the dark counts caused by the thermal carriers. Therefore, there are many efforts to suppress the afterpulse by means of the avalanche signal detection with a low avalanche gain. Among them, we have applied the sinusoidal gate operation of InGaAs/InP APD (SG-APD) that achieved much higher gate repetition frequency than that of conventional gate operations.