Temporal correlations of spectrally narrowband photon pair sources

Abstract

Wereport on theoretical and experimental investigations of time-resolved cross- and auto-correlation measurements of spectrally narrowband photon pairs generated in sources based on parametric down conversion in resonant waveguide structures.Weshow that time-resolved measurements provide detailed and useful information about the spectral and modal structure of the bi-photon state. The shape of the cross-correlation function is asymmetric with exponential decays determined by the lifetimes of the signal and idler photons in the cavity. The time-resolved auto-correlation has Lorentzian shape. Themeasured g (2) (0) value convolutedwith the detectorwindows andmode beating can be used to characterise the spectral longitudinal mode behaviour. The temporal width of the auto-correlation function is more than two times longer that the cross-correlation time. This reveals that the spectral bandwidth of the single-photon component is much broader than the spectral width of the two-photon component.