Theory of PDC in a Continuous Variables Framework and Its Applications to the Absolute Calibration of Photo-Detectors

The aim of this review is to provide a unitary and extensive theory of parametric down conversion beyond the limit of low gain and single mode regime, addressing the problem of measuring the twin beams and the intensity correlations by means of analog detectors. An important example of application can be found in optical metrology: the absolute calibration of analog photo-detectors.