Patent ID: 7245424

Claim:
A laser comprising: a closed loop fiber wherein the closed loop fiber includes an optical gain fiber; means for introducing a pump light into the closed loop fiber; and means for providing an output from the closed loop fiber; wherein the optical gain fiber comprises a modified silica glass configured to provide a reduction in the multiphonon quenching for a rare-earth dopant; wherein said modified silica glass comprises SiO 2 in a host material, a rare-earth oxide dopant selected from the group consisting of Tm 3+ , Ho 3+ and Tm 3+ sensitized —Ho 3+ , and a first SiO 2 modifier; and wherein said first modifier is a 3+ cation dopant and is selected from the group consisting of Ga, Y, and combinations thereof, configured such that said first modifier reduces multiphonon quenching of said rare-earth dopant contained therein.