Abstract

Upconversion lasers need host materials with low effective phonon energies to minimize the non-radiative decay rates of the rare-earth dopant excited energy levels involved in the multi-step pumping process. Fluoride crystals like LiYF₄ indeed show low effective phonon energies as compared to oxide materials and can be grown by the Czochralski method. Er³⁺:LiYF₄ room-temperature continuous-wave upconversion lasers emittmg m the green spectral region have successfully been demonstrated for the first time in our laboratory [1]. Efficient excitation of the green emittmg ⁴S_3/2 level was achieved by pumping at 810nm or 970nm, where semiconductor laser diodes are commercially available. Therefore, the realization of an all-solid-state erbium-doped fluoride-crystal upconversion laser can be envisaged.

© 2000 IEEE