Analysis of low intensity square wave modulated light beams by measuring the Laplace or squared cosine transform of the time-interval probability

In this paper we study the possibility of analyzing a low-intensity light signal modulated by a square wave by measuring the Laplace or the squared cosine transform of the time interval probability. The error in the determination of the period of the signal is studied and compared with that obtained from the correlation function g⁽²⁾ (τ). We conclude that measurement of the squared cosine transform is a more advantageous method than measurement of g⁽²⁾ (τ) for low intensity light beams, the advantage increasing as the intensity of the light beam decreases. This technique can, for instance, be applied to the fields of laser Doppler velocimetry and optical communications.