Ytterbium-doped solid core photonic bandgap fiber for laser operation around 980 nm

We report on the design and characterization of an ytterbium-doped solid core photonic bandgap fiber laser operating at 977 nm. By adjusting the fiber optogeometrical parameters, we favored laser gain in the three level configuration thanks to the introduction of bandgap losses in the wavelength range above 1000 nm; avoiding thus laser operation in the four level configuration. A slope efficiency of ∼65% has been obtained for a 99%-4% laser cavity.