On the wavelength range and quantum efficiency of three-micron laser emission in concentrated Er-systems

Abstract
A generatized model for stationary three-micron laser emission governed by energy transfer processes in concentrated Er-systems is presented. Explicit analytical equations for the photon flux density in the resonator for a given wavelength is obtained as a function on system parameters (rates of up-conversion processes from the laser levels, efficiency of cross-relaxation processes, cross section of emission, losses, crystal field splitting of levels, lifetimes of laser levels, dopant concentration), on pump characteristics (wavelength, intensity) and temperature. These equations describe in a consistent way the existing data on stationary laser emission in concentrated Er systems and suggest possible ways to control and improve the characteristics of emission.