Tm^3+ doped barium gallo-germanate glass single-mode fibers for 20 μm laser

Tm³⁺ doped barium gallo-germanate (BGG) glass has emerged as a promising 2.0 μm laser material offering excellent optical property. Unfortunately, low anti-crystallization ability and high OH⁻ content of the glass have hindered the fabrication of high-quality optical fibers. In this paper, La₂O₃ and Y₂O₃ were added into BGG glass to enhance the glass anti-crystallization ability. Additionally, the optimized Reaction Atmosphere Procedure (RAP) was utilized to minimize OH⁻ content. Continuous Tm³⁺ doped BGG glass single-mode (SM) fibers were successfully obtained by the rod-in-tube technique for the first time to our best knowledge. A 140 mW all-fiber laser at 1.95 μm was demonstrated using a 9.7-cm-long as-drawn Tm³⁺ doped BGG glass SM fiber upon excitation of a home-made 1568 nm fiber laser.