Effect of Excitation Migration and Upconversion in Highly Erbium-doped Glass Micro-sphere Lasers

Abstract

Abstract. Excitation migration and upconversion process in the Erbium-doped silica-alumina glass microsphere lasers with concentrations of 2500-4000 ppm were investigated in detail. The experiment shows that under 976 nm excitation, the intense of up-conversion emission at 523, 546 and 657 nm, corresponding to the transitions 2 H 11/2 → 4 I 15/ , 4 S 3/2 → 4 I 15/2 , and 4 F 9/2 → 4 I 15/2 , respectively, depends on the erbium content, migration of excitation and pump power. The excitation migration has strongly influenced on the threshold and Red shift of lasing wavelength and migration-assisted up-conversion process leads to degraded amplification performance of microsphere lasers made by silica-alumina glasses with different contents of Er-ions.