Efficient laser operation with low loss Nd3+-doped phosphate glass fiber under direct pumping

For the first time, we have demonstrated efficient 1054 nm laser output with low loss Nd3+-doped phosphate glass fibers at room temperature using an 888 nm laser diode as the direct pumping source. Therein, the home-made Nd3+-doped phosphate glass fiber is the key for laser performance improvement. The transmission loss of the large-core single-cladding Nd3+-doped phosphate fibers prepared by the novel peeled-off isolated stacked extrusion method is as low as 1.1 dB/m at ∼1 μm. On this basis, a low-loss Fabry-Perot cavity is constructed by precisely controlling the relative distance between the fiber end facet and the cavity mirror with a microscope. The record-breaking optical-to-optical efficiency of Nd3+-doped phosphate glass fiber lasers, 50.2% is achieved with the maximum output power of 6.71 W. During laser operation, the output laser power does not roll over, even at high pump powers. The output laser power is limited only by the available pump power. This work will lay a solid foundation to the high-power fiber laser fabrication, and will find many applications in the future.