Miniature modules for single-photon detection

Miniature detector modules including Single-Photon Avalanche Diodes (SPADs) and the associated electronic circuitry (an integrated Active-Quenching Circuit - iAQC), are here presented. These modules are able to detect single photons, and can be used in any application where very faint and/or fast optical signals must be measured. Thanks to the small size and the limited power consumption of the CMOS design of the iAQC, these modules can be housed in standard packages (e.g. TO-8) and can be fitted also in restricted spaces within instrumentation systems, such as microscopes or cryostats. The employed quenching circuit is the first fully monolithic iAQC reported in literature; US patent and European patents have been applied for its design. It can swiftly quench and reset the SPAD biased up to 40V above breakdown. The total counting deadtime is less than 50ns, corresponding to a maximum saturated counting rate of 20Mcounts/s. The circuit provides also a gated-sensor operation mode, with minimum gate-on time interval of about 50ns. The compactness, low-power design and high reliability of the iAQC make it suitable also for multi-sensor systems, such as linear and square arrays of SPAD detectors.