Phosphate glass core and silica cladding laser fiber

The goal of the present work is to develop a composite Yb-Er doped optical fiber that combines the advantages of both phosphate and silica glasses. In the lasing experiment the output fiber of 4W at 1064 nm laser was spliced with high-reflective fiber Bragg grating having resonance wavelength 1535 nm with core diameter corresponding to the Yb-Er fiber. The grating was then spliced with Yb-Er fiber having the length of 0.9 m. The Yb-Er laser resonator was formed by the Bragg grating and cleaved fiber end. Maximum output power of 130 mW and the slope efficiency 4% were obtained. Relatively small efficiency value in the first experiment can be explained by high splice connection losses. Thus an optical fiber with Yb-Er co-doped phosphate glass core in a silica cladding was fabricated. 1.54 μm laser action in it was demonstrated under core pumping into Yb absorption band.