Time-domain diffuse optics with 8.6  mm² fast-gated SiPM for extreme light harvesting

Fast time-gated single-photon detectors demonstrated high depth sensitivity in the detection of localized absorption perturbations inside scattering media, but their use for in vivo clinical applications-such as functional imaging of brain activation-was impaired by their small (<0.04mm²) active area. Here, we demonstrate, both on phantoms and in vivo, the performance of a fast-gated digital silicon photomultiplier (SiPM) that features an overall active area of 8.6mm², overcoming the photon collection capability of established time-gated single-pixel detectors by orders of magnitude, enabling deep investigations within scattering media and high signal-to-noise ratios at late photon arrival times.