The PDM single-photon counting detectors can detect light in the 375 nm to 1000 nm wavelength range. The standard TTL output pulses provide better than 250 ps timing resolution. However, the PDM can also be configurated to generate an additional output pulse (NIM standard) able to provide better than 50 ps FWHM photon timing resolution.

The excellent photon detection efficiency and superior timing resolution are obtained through the combination of custom epitaxial silicon SPAD coupled to an Active Quenching Circuit (AQC) specifically designed and optimized for photon counting applications. The SPAD is thermally stabilized by a thermoelectric cooler, to ensure stable performance despite ambient temperature changes.

The PDM GATE IN input can be used to switch on and off the detector during specific time windows for better noise rejection and increased signal-to-noise ratio. The PDM GATE IN input should only be used to gate ON or OFF the SPAD with minimum gate ON or GATE OFF times in the orders of few tens of microseconds or longer, as it is not designed to accept high repetition external trigger signals.

The PDM maximum saturated count rate is around 13 Mcps. It is good practice, in order to avoid non-linearity errors in counting applications, to keep a maximum count rate of at least four or five times smaller than the saturation level. The module is fully protected against light overload.

The PDM is available with two optical interfaces: a free space optical window and a fiber connectorized version that guarantees > 80% coupling efficiency with selected fibers.