Single photon avalanche diode for single molecule detection

A commercially available single photon avalanche photodiode in a passively quenched circuit is used with time-correlated single photon counting modules to achieve subnanosecond time response together with high quantum efficiency and low dark noise. These characteristics are required for experiments in single molecule detection and spectroscopy in which time-gated detection schemes are used. By tightly focusing the input light onto the active area, a quantum efficiency of over 50% and a single photon timing jitter of 158 ps full width at haff-maximum are achieved. In addition, the full width at one-hundredth maximum, which is of greater importance for time gating, is 790 ps, comparable to that from a microchannel plate photomultiplier. Measurements of the detector dead time, and the quantum efficiency, dark counts, time response, and pulse height distribution for different operating conditions are also reported,