Gigacount/second Photon Detection Module Based on an 8 × 8 Single-Photon Avalanche Diode Array.

In this letter we present a compact photon detection module, based on an 8×8 array of single-photon avalanche diodes (SPADs). The use of a dedicated silicon technology for the fabrication of the sensors allows us to combine large active areas (50-μm diameter), high photon detection efficiency (49% at 550-nm wavelength) and low dark count rate. Thanks to a fully parallel architecture, the module provides voltage pulses synchronous to each photon detection for a maximum global count rate exceeding 1 Gcps. These properties makes the system suitable for operation in two different free-running modes. The first, suitable to acquire faint signals, allows multi-spot acquisitions and can be used to considerably reduce the measurement time in applications like single-molecule analysis. With the second it is possible to use all the pixels in a combined mode, to extend and move the dynamic range of the module to very high count rates and to attain number resolving capabilities.