Abstract
A study of the nonclassical features of the cavity radiation of a nondegenerate three-level cascade laser coupled to a two-mode vacuum reservoir is presented. It turns out that the generated radiation violates CauchySchwarz inequality in the regime of lasing without population inversion. The nonclassical photon number correlation, in general, is found to decrease with the injected atomic coherence and linear gain coefficient, whereas the entanglement increases with the rate at which the atoms are injected into the cavity. Moreover, comparison between the photon number correlations and entanglement reveals that for some parameters under consideration they can be equal, which indicates that entanglement can be quantified via photon count measurements.