SPADs and TDCs for photon-counting, timing and gated-imaging at 30 ps resolution and 60% efficiency

The growing interest for very sensitive, single-chip, cost-effective imagers with single-photon sensitivity, ultra-precise time-tagging capability and ease of custom on-chip processing, is driving the development of Single-Photon Avalanche Diode (SPAD) single-pixel modules, linear array chips, and eventually fully embedded SPAD imagers with high performance and easy programmability in a single monolithic microelectronic chip. We report on SPAD imagers developed in standard, cost-effective, CMOS and BCD microelectronic technologies, able to provide 2D (two dimensional) images of the sample, with photon-counting data (i.e. number of detected photons) per pixel, and time-resolved 3D (two spatial dimensions, plus the time-tag info) videos at very high frame-rates up to hundreds of kframe/s (i.e. one frame every few μs), with picosecond resolution in measuring the photon arrival time. We detail specific SPAD imagers and modules, conceived and deployed for specific applications in different fields, such as medical and microscopy. Namely a high timing resolution single pixel and a SPAD photon-counting camera, for Fluorescence Lifetime Imaging (FLIM) and a large area multi-photon coincidence detector with integrated 7 ps resolution Time to Digital Coverter.