Estimate of the gain of an active medium from the superradiance decay kinetics

An analysis is made of a one-dimensional problem involving superradiance of four-level active media. The rate equations for the populations and the transport equations for the superradiance fluxes are used to derive differential equations for the description of the behavior of the integrated population and the observed superradiance flux in the active medium excited by the pump flux. A detailed analysis is made of the superradiance decay. Analytic dependences are obtained to describe the decay of the normalized superradiance flux. The gain of the active medium at the onset of decay occurs as the parameter in these dependences and they are used as the basis of a technique for obtaining upper and lower estimates of this parameter.