|Thesis abstract: |
In the last years, an increasing number of applications require the use of photodetectors able to acquire fast and weak light signals, down to the single-photon level. For this purpose Single-Photon Avalanche Diodes (SPADs) can be successfully exploited, achieving high detection efficiency with low noise and high timing resolution. Another advantage of a SPAD detector is the possibility of turning it ON and OFF very quickly and efficiently. This gating technique is useful to perform a time selection of incoming photons, for example in cases where a filtering based on light wavelength or polarization is not possible. Moreover, the gated-mode can also be used to reduce the effect of Dark Count Rate (DCR) and afterpulsing contribution, improving the signal-to-noise ratio of the measurement. This PhD research activity aims to develop new electronic instrumentation for time-gating SPAD detectors, starting from a single-pixel photon counting module with gating transitions shorter than 200 ps and repetition rates up to 100 MHz and moving towards arrays of time-gated SPADs, thus improving imaging capabilities, data throughput and measurement time. The module will be exploited in different applications like for example time-resolved diffuse optical spectroscopy, fluorescence life-time microscopy and ultrafast time-of-flight imaging. These exploitations will be carried on in collaboration with world-leader research groups, exploring new application-specific improvements in order to achieve the best performance from time-gated SPAD instruments.