Multiphoton detection using visible light photon counter

Visible light photon counters feature noise-free avalanche multiplication and narrow pulse height distribution for single photon detection events. Such a well-defined pulse height distribution for a single photon detection event, combined with the fact that the avalanche multiplication is confined to a small area of the whole detector, opens up the possibility for the simultaneous detection of two photons. In this letter, we investigated this capability using twin photons generated by parametric down conversion, and present a high quantum efficiency (similar to 47%) detection of two photons with good time resolution (similar to 2 ns), which can be distinguished from a single-photon incidence with a small bit-error rate (similar to 0.63%). (C) 1999 American Institute of Physics. [S0003-6951(99)00307-1].