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 (<0.04 mm2) active area. Here, we demonstrate, both on phantoms and in vivo, the performance ofa fast-gated digital silicon pho- tomultiplier (SiPM) that features an overall active area of 8.6 mm2, 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.