Measurement of the spectral properties of the two-photon state generated via type-II spontaneous parametric down-conversion

We report the complete measurement of the spectral properties of photon pairs generated via spontaneous parametric down-conversion. The measurements, which include not only single-photon spectra, but also two-photon joint spectra, were performed for both cw and ultrafast pumping configurations. In agreement with theoretical predictions, the spectra for the ultrafast pumped case reveal asymmetries not present with cw pumping.