  Compact silicon integrated devices, such as micro-ring resonators, have
recently been demonstrated as efficient sources of quantum correlated photon
pairs. The mass production of integrated devices demands the implementation of
fast and reliable techniques to monitor the device performances. In the case of
time-energy correlations, this is particularly challenging, as it requires high
spectral resolution that is not currently achievable in coincidence
measurements. Here we reconstruct the joint spectral density of photons pairs
generated by spontaneous four-wave mixing in a silicon ring resonator by
studying the corresponding stimulated process, namely stimulated four wave
mixing. We show that this approach, featuring high spectral resolution and
short measurement times, allows one to discriminate between nearly-uncorrelated
and highly-correlated photon pairs.
