Dual wavelength visible upconversion laser

Abstract

Laser operation has been obtained at 551 and 671 nm by pumping 5% Er:YLiF4 at 791 nm. Time dependence studies of the emission show that the excitation process has a component related to cooperative energy transfer, and a component related to stepwise multiple photon absorption. Self-Q-switched operation at 551 nm is seen to impart a time dependence to an otherwise cw output at 671 nm.