  We measure the joint temporal intensity of signal and idler photon pairs
generated by spontaneous four wave mixing in a silicon nitride microresonator
by time-resolved coincidence detection. This technique can be applied to any
high-Q optical cavity whose photon lifetime exceeds the duration of the pump
pulse. We tailor the temporal correlation of photon pairs by using a resonant
interferometric coupler, a device that allows us to independently tune the
quality factors of the pump and signal and idler resonances.Temporal
post-selection is used to accurately measure the temporal emission of the
device, demonstrating a purity of 98.67(1)%.
