Abstract

Cooperative multi-ion energy transfer and two-step excitation processes have been used to achieve population inversion and laser action in erbium-doped YLiF₄ and BaY₂F₈. Pulsed and cw experiments have been carried out to provide details of the pumping pathways and to identify systems having particularly favorable values for the upconversion transfer coefficient Examples of laser emission at wavelengths shorter than the cw pump will be described for YLiF₄. Pulsed IR laser output has been demonstrated in BaY₂F₈,:Er, where the time dependence confirms efficient cooperative energy transfer associated with the ⁴I_13/2 level.

© 1989 Optical Society of America