High-power tunable red laser based on double-cladding Pr3+-doped fiber

•Highest output power of red laser available in the visible fiber laser field.•Red-wavelength-tunable fiber laser with double-cladding Pr3+-doped fluoride fiber realized for the first time.•Provides a way to implement high-power fiber lasers in other visible wavelengths. A high power visible laser is produced by combining double-cladding fluoride fiber, a specially fiber structured suitable for high power visible laser generation. Here, a double-cladding Pr3+-doped red fiber laser with an output power of 3.65 W and slope efficiency of 22 % had been developed in this research, making it the highest output power ever obtained in fiber lasers. In addition, the first tunable double-cladding fiber laser was also created, with a tuning range of near 9 nm from 632.60 nm to 641.48 nm. The free-running laser also achieved more than 500 mW at the center wavelength of 636.38 nm. With this tunable laser, new ground is broken in the field of double-cladding fiber tuning.