Spectroscopy and 2 μm laser behaviors of Al3+/Ho3+ CO-doped silica fiber

Abstract A Ho 3+ -doped silica glass, 0.08Ho 2 O 3 –1.6Al 2 O 3 –98.32SiO 2 (mol%), was prepared by the sol–gel method combined with high temperature sintering. The 2 μm luminescence properties of the Al 3+ /Ho 3+ co-doped silica core glass were investigated. A single-mode double cladding Al 3+ /Ho 3+ co-doped silica fiber with a 15 μm core diameter and 0.08 core numerical apertures was prepared. Pumped with a 1.95 μm Tm 3+ fiber laser, 320 mw laser output centered at 2040 nm with M 2 factor of 1.14 was obtained from a 150-cm-long double-cladding fiber. The laser has a threshold of 850 mw launched power with a slope efficiency of 48.46%. For the first time a robust single-mode 2 μm fiber laser was realized in a fiber with Al 3+ /Ho 3+ co-doped silica core glass prepared by the sol–gel method.