Correction for the detector-dead-time effect on the second-order correlation of stationary sub-Poissonian light in a two-detector configuration

Abstract

Exact measurement of the second-order correlation function g((2))(t) of a light source is essential when investigating the photon statistics and the light generation process of the source. For a stationary single-mode light source, the Mandel Q factor is directly related to g((2))(0). For a large mean photon number in the mode, the deviation of g((2))(0) from unity is so small that even a tiny error in measuring g((2))(0) would result in an inaccurate Mandel Q. In this work, we address the detector-dead-time effect on g((2))(0) of stationary sub-Poissonian light. It is then found that detector dead time can induce a serious error in g((2))(0) and thus in Mandel Q in those cases even in a two-detector configuration. Utilizing the cavity-QED microlaser, a well-established sub-Poissonian light source, we measured g((2))(0) with two different types of photodetectors with different dead times. We also introduced prolonged dead time by intentionally deleting the photodetection events following a preceding one within a specified time interval. We found that the observed Q of the cavity-QED microlaser was underestimated by 19% with respect to the dead-time-free Q when its mean photon number was about 600. We derived an analytic formula which well explains the behavior of the g((2))(0) as a function of the dead time.