Joint spectral measurements at the Hong-Ou-Mandel interference dip

We employed a 2-channel single-photon detection system with high detection efficiency and low jitter to characterize the joint spectral probability distribution of correlated photons emerging from a Hong-Ou-Mandel interference arrangement. The high detection efficiency allows simultaneous measurement of all frequency components emerging from the source. The results show that the photons show an evolution from bunching to anti-bunching by the entangling beamsplitter of the HOM interferometer.