Quantum efficiency of the self-frequency-doubling laser material

Abstract
In this paper, the quantum efficiency of the laser crystal has been measured using a method based on the simultaneous measurement of photoacoustic and photoluminescence signals within a broad wavelength excitation range (700-850 nm). A quantum efficiency is determined. This low quantum efficiency is explained in terms of a high multiphonon relaxation rate from the metastable state involving about three effective phonons of energy 1346 .