Abstract

An efficiency of nearly 30% has been achieved in an erbium upconversion laser operating at 0.85μm with excitation at 1.5μm. Continuous-wave excitation of fluorescence from the upper laser level is shown to vary as the cue of the pump intensity, and time-resolved studies are used to distinguish between various multiphoton and multiatom processes that potentially contribute to the population inversion. We have been able to show that the inversion is overwhelmingly dominated by a three-body cooperative process, which we refer to as triopumping. The high efficiency of this continuous-wave trio laser is particularly remarkable in view of its operation on a self-terminating transition with lower laser-level pumping.

© 1990 Optical Society of America