Widely Tunable Narrow-Linewidth Large Mode Area Er³+/Yb³+ Codoped Double-Clad Fiber Laser

A widely tunable narrow-linewidth large mode area (LMA) Er³⁺/Yb³⁺ codoped double-clad fiber laser is demonstrated. By using a blazed grating as wavelength selection element, the laser was tunable over a range of 38.16 nm from 1531.98 nm to 1570.14 nm, covering nearly the whole fluorescence spectrum. The laser linewidth was less than 0.08 nm for all tuned wavelengths. The maximum output power was 650 mW at 1543.444 nm, with a slope efficiency of 28%.