Photon counting statistics with thermal light having a multiple-peak spectrum

We consider the photon-counting statistics with polarized thermal light having arbitrary rational spectral profile. The method is illustrated for a light beam having a two-peak symmetric Lorentzian spectrum. The associated integral equation is converted into a differential equation and the eigenvalues are determined. Using the standard techniques of contour integration, an explicit expression is obtained for the generating function valid for an arbitrary value of the counting interval.