Laser action from a femtosecond laser written Yb: phosphate glass waveguide

Single-transverse-mode active waveguide with circularly symmetric cross-section was written in Yb: phosphate glass using slit-shaped infrared femtosecond laser in low repetition rate regime. The refractive index profile reconstructed from the measured near field mode indicates that the waveguide is composed of a core with a depressed index cladding. The enhanced refractive index contrast due to the existence of cladding effectively supports waveguiding. Laser operating at 1030 nm was demonstrated when the waveguide was pumped at 976 nm. A maximum output power of 33 mW was obtained, resulting in a record slope efficiency of 18.5%.