Fully parallel correction algorithm for real-time distortion-free TCSPC operation via direct dead time measurement.

Time-correlated single-photon counting (TCSPC) is a pivotal technique for time-resolved photonic applications requiring exceptional temporal resolution. Unfortunately, conventional TCSPC has long been confined to a low-speed regime due to pile-up distortion, commonly regarded as a statistical bias favoring the detection of early-arriving photons within each excitation cycle at high count rates. A recently introduced measurement strategy theoretically extends distortion-free TCSPC operation into the multi-photon regime by leveraging an auxiliary histogram alongside the conventional photon arrival-time distribution, which explicitly maps the time-resolved availability of the detection system. Within this framework, pile-up distortion is recast as a deterministic consequence of the time-varying sensitivity of the detection system and can be eliminated through direct measurement of its operational state. However, real-time operation remains precluded by the sequential construction of the auxiliary histogram, as implemented in existing reconstruction schemes. To address this limitation, we introduce a fully parallel approach that removes this computational bottleneck, advancing TCSPC techniques to more practical applications beyond laboratory settings. We present a closed-form formulation of the proposed strategy and demonstrate its experimental validation on dedicated modern processing architectures.