Heavily Tb 3+ doped multi-component phosphate glass fibers for green fiber lasers

Heavy rare earth (RE) ion doped glass fibers make it possible to obtain high gain and high output power per unit length. It is known that high concentration of RE ions can be incorporated into multi-component phosphate glasses, which are usually used to fabricate high performance gain fibers. However, the increasing doping concentration of RE ions is mainly limited by the concentration quenching effect and crystallization during the fiber drawing process by the conventional rod-in-tube technique. In this work, no fluorescence quenching was observed in the prepared multi-component phosphate glasses even when Tb3+ doping concentration reached 16 mol %. Then, heavily Tb3+ doped multi-component phosphate glass fibers with silicate glass cladding were successfully drawn by a molten core method, which can effectively solve the crystallization problem caused by heavily RE ions doping. To the best of our knowledge, 16 mol % is the record high Tb3+ ion in phosphate glass fibers for green laser. An intense 540 nm green emission with fluorescence lifetime as long as 1.85 ms was obtained from the as-drawn fibers, showing promising applications for green fiber lasers.