Diode pumped visible Dy3+-doped silica fiber laser: Ge-co-doping effects on lasing efficiency and photodarkening

Abstract We present the first demonstration of visible laser oscillation in the Dy3+-doped silica fiber pumped by a 451 nm InGaN laser diode. It was found that Ge-co-doping plays the following important roles of laser oscillation: (1) to reduce the Rayleigh scattering loss, (2) to suppress the X-ray-induced and pump-induced photodarkening (PD), and (3) to increase lasing slope efficiency. In a fiber with 0.46 wt% Dy, 1.8 wt% Ge, and 0.54 wt% Al, the slope efficiency is 22.0% at 582.5 nm, and the maximum output power is 18.4 mW.