Abstract

Upconversion lasing has been reported by Allain et al.¹ in single mode Ho³⁺-doped fiber at room temperature. We extend the work of Allain et al. and present here a detailed study of the upconversion lasing characteristics of a Ho³⁺-doped fluorozirconate fiber. Our fiber has an 11 pm core diameter (multi-mode for both pump and lasing wavelengths) and was doped with a concentration of 1000 ppm Ho³⁺. The fiber exhibits strong upconversion fluorescence in a band centered at around 550 nm. The peak of the upconversion fluorescence was found to depend on fiber length. With a pump wavelength of 647 nm, we have observed cw lasing in this fiber at 550 nm at room temperature with a threshold pump energy of 155 mW. We have observed lasing for pump wavelengths from 643 to 651 nm. The laser cavity consisted of two external dielectric mirrors butted against the uncoated fiber ends. Coupling into the fiber was accomplished by using a 10× microscope objective.

© 1992 Optical Society of America