Time dependent study of femtosecond laser written waveguide lasers in Yb-doped silicate and phosphate glass

We study the time dependent performance of distributed feedback (DFB) waveguide lasers (WGLs) fabricated with an ultrafast laser in Yb-doped phosphate and silicate glasses for the first time. After 30 hours of continuous pumping, the phosphate based laser performance degraded while the silicate based laser surprisingly improved in performance. Additional studies of grating behavior during optical pumping imply that the propagation loss for the silicate glass waveguides reduces over time. (C) 2015 Optical Society of America