Fast-gated single-photon detection module with 200 ps transitions running up to 50 MHz with 30 ps resolution

We present a compact instrument able to quickly time-gate a silicon Single-Photon Avalanche Diode (SPAD) to be used in advanced gated Time-Correlated Single-Photon Counting (TCSPC) setups, like time-resolved optical spectroscopy, optical mammography, optical molecular imaging. The detection module can be used to boost the photon counting dynamic range, thanks to the fast transitions between the OFF and the ON state of the detector. The module embeds into a single box (11 cm x 15 cm x 24 cm) all components needed to operate a SPAD detector in fast time-gated mode and to output a standard NIM timing signal. The module includes: i) an ultra-fast pulse generator, based on MMIC components, to enable and disable the detector in less than 200 ps for very short and well-defined time slots, ranging from less than 1 ns up to 10 ns with 10 ps steps, at a repetition rate up to 50 MHz; ii) the silicon SPAD itself together with optical assembly to focus photons from an optical fiber onto the active area; iii) a passive quenching/active reset electronics, needed for optimal detector operation; iv) a low time-jitter comparator, to detect avalanche ignitions with less than 30 ps (FWHM) jitter and to generate a standard NIM output; v) a service board containing power supply, microcontroller, and USB link, to remotely set and control all instrument parameters.