We report the measurement of nonclassical photon statistics at the outputs of 2×2 and 3×3 fiber couplers resulting from quantum-mechanical second-order interference of entangled photon pairs from a parametric down-conversion source. This is a demonstration of the bunching of bosons at the outputs of fiber multiports. Single-mode fibers provide precise wavelength selection from the down-conversion source spectrum, thus yielding very long coherence times and good collection efficiency without the need of interference filters. Two-photon interference visibilities close to the theoretical maximum were achieved in the experiments. © 1996 The American Physical Society.

• Received 14 February 1996

DOI:https://doi.org/10.1103/PhysRevA.54.893