Monolithic fiber laser oscillation at 717nm

We report a monolithic Pr3+-doped ZBLAN fiber laser operating at 717.7 nm, directly pumped by a commercial 441 nm laser diode. The linear cavity is formed by a pair of fiber Bragg gratings (FBGs), achieving a maximum output power of 188 mW. To the best of our knowledge, this represents the first demonstration of monolithic fiber laser oscillation at 717.7 nm, filling a critical gap in deep-red fiber lasers. Moreover, the all-fiber monolithic configuration provides excellent thermal management at the pump injection end, paving the way for high-performance visible fiber lasers.