Low-Cost and Compact Single-Photon Counter Based on a CMOS SPAD Smart Pixel

We present a single-photon counter based on a silicon single-photon avalanche diode (SPAD) fabricated in a 0.35-μm CMOS technology. The detector is monolithically integrated with a front-end circuit and a digital pulse output driver. External components are kept to a minimum, and the resulting instrument is low-cost, low-power, and compact, being housed into an industry-standard 1-in aluminum optical mounting tube. It features a maximum power consumption of just 250 mW from a USB link. The embedded 50-μm-diameter SPAD has high photon detection efficiency in the visible range (55% at 420 nm), low noise (<;100 Hz at room temperature), low timing jitter (<;100-ps full-width at half-maximum), and very low afterpulsing probability (down to 1% with 60-ns hold-off time). The high performance, compactness, and low cost enable many unexplored applications in life sciences, personal health care, industrial quality check, quantum physics and others, where it is required to count single photons and to measure their arrival time.