Nd3+ doped phosphate glass optical fibre lasers

We report on the fabrication of three different phosphate glasses using a custom designed glass composition (P₂O₅ - Li₂O - Al₂O₃ - B₂O₃ - BaO - PbO - MgO) with the aim to fabricate a Nd³⁺-doped double cladding optical fibre laser emitting at 1.06 μm. By changing properly the concentration and types of compounds present in our phosphate glass, the refractive indexes of the three glasses were adjusted in order to obtain an adequate numerical aperture between core and inner cladding, and between inner and outer cladding, while maintaining similar thermo-mechanical properties in view of the fibre drawing process. Physical and thermal properties of the glasses are presented and discussed. Spectroscopic properties of the core glass are described. In order to optimize Nd³⁺-doped fibre laser design, a numerical analysis of the lasers was performed and resulting design curves are presented. With the aim to test the feasibility of the double cladding optical fibre fabrication process and materials, a Yb³⁺/ Er³⁺ co-doped double cladding fibre based on the same glass host composition, was drawn and preliminary characterized.