High Speed Single-photon Detection Based On Avalanche Photodiode

As a weak signal detection technology,single photon detection has played a key role in the quantum communication.With the development of quantum communication,it is important to develop the single-photon detector with a high efficiency,high speed and low noise.So far the InGaAs/InP avalanche photodiode(APD)has become the most widely used single-photon detector at telecom wavelengths due to its advantages of high detection efficiency and low power consumption.The InGaAs/InP APD typically works on gated Geiger-mode,which would generate a gate transient caused by the capacitive response,and it is quite difficult to discriminate small avalanche signals from the transient.In order to extract the avalanche signals,subsequent electric circuits need to be brought in to suppress the transient.Here,we present a new detection system in which the gating is synthesized from the 1st and 2nd harmonics of the fundamental frequency of 1.25 GHz.With phase and amplitude control for each harmonic,we form<33 Ops bias gates,which can provide shorter gate duration than a purely sinusoidal gate of the same amplitude.Meanwhile using a low pass filter to suppress the gate transient to discriminate the avalanche signal.