Unidirectional dual-wavelength pumping at 805 and 975 nm of a Tm<sup>3+</sup> -doped silica double-clad fiber laser that has been codoped with Yb<sup>3+</sup> is demonstrated. With equal 2-wt. % concentrations of the Tm<sup>3+</sup> and Yb<sup>3+</sup> ions, slope efficiencies of 49% (57%) and 35% (40%) with respect to the launched (absorbed) pump power of the 805- and 975-nm pump wavelengths, respectively, were obtained. Efficient Yb<sup>3+</sup>→ Tm<sup>3+</sup> energy transfer and efficient cross relaxation combined with minimal upconversion losses were thus operating. At the maximum output power of 18 W, the fiber laser operated at a center wavelength of 2050 nm.
© 2003 Optical Society of America
Stuart D. Jackson, "Power scaling method for 2-μm diode-cladding-pumped Tm3+-doped silica fiber lasers that uses Yb3+ codoping," Opt. Lett. 28, 2192-2194 (2003)