Statistical Properties of Nondegenerate Three-Level Laser

We study the squeezing and statistical properties of the light produced by nondegenerate three-level lasers coupled to a vacuum reservoir, in which two different nondegenerate three-level atoms are injected at constant rate into the cavity. Applying the pertinent master equation, we obtain the stochastic differential equations associated with the normal ordering. Making the use of the solutions of the resulting differential equations, the quadrature variances and the mean and variance of the photon number sum and difference are described. We see that the mean and variance of the photon number difference is positive; this fact indicates that the mean photon number of mode a, emitted from the top level, is greater than that of mode b, emitted from the intermediate level of the three-level atom. Moreover, we find that the mean and variance of the photon number difference decreases as η increases. We observe that the squeezing is higher for large values of linear gain coefficient, and the maximum squeezing occurs when the population of the atoms in the bottom level is slightly greater than that of the top level.