Abstract

Laser action based on the visible and infrared transitions from the ⁴S_3/2 and ⁴I_11/2 states, respectively, of the Er³⁺ ion have been demonstrated in different crystals.^1,2 We have studied the upconverted yellow and red fluorescence in erbium aluminum garnet, following two-photon (TP) excitation by the infrared radiation from a frequency tunable dye laser. Experimental results suggest that in addition to direct two- photon absorption, cross relaxation and stepwise TP processes are operative in exciting the terminal states of the transitions.

© 1994 Optical Society of America