08 Nov 2007
A Chinese research team has demonstrated an integral gated-mode single-photon detector that monitors the charge number of an avalanche pulse rather than the peak current.
Avalanche photodiodes (APD) are commonly used in single-photon detectors (SPDs) for quantum cryptography techniques. Currently, the most effective performance mode for APDs is gated-mode operation. Although this method works well, the use of short-gate pulses leads to the production of two transient spikes that obscure the photon-induced avalanche pulses.
The researchers describe the design and fabrication of an integral gated-mode single-photon detector (IGSPD) in which the transient spikes in conventional gated-mode operation are cancelled completely by integrating. This allows improved performance of a single photon detector while using the same avalanche photodiode (J. Phys. D: Appl. Phys. 40 6922).
The team has demonstrated that at telecom wavelengths the system achieves a detection efficiency of 29.9% at a dark count probability per gate equal to 5.57x10−6/gate (1.11 × 10−6 ns−1) at 1550 nm.
The developed IGSPD shows improved performance over traditional gated mode SPDs, and is expected to be helpful in future device design.