A mathematical model was developed to obtain the population inversion of the atoms in laser field in a laser cavity by considering the electric field in the optical cavity and the atomic states of the medium to be quantized. The master equation of the density operator of the laser field was studied analytically and numerically. Using coherent states, the Fokker-Plank equation for the phase space density for the laser field was solved analytically for the time dependent and steady state situations. The laser field above the threshold can be represented by a randomly phased mixture of coherent states. As the pump parameter increases in the laser process, the phase density becomes narrower, tending toward a delta function, creating a coherence laser field.
International Letters of Chemistry, Physics and Astronomy (Volume 56)
K.M. Priyashanka and K.A.I.L. Wijewardena Gamalath, "Coherent States in a Laser Cavity", International Letters of Chemistry, Physics and Astronomy, Vol. 56, pp. 47-62, 2015