  A femtosecond laser-written monolithic waveguide laser (WGL) oscillator based
on a distributed feedback (DFB) architecture and fabricated in ytterbium doped
phosphate glass is reported. The device lased at 1033 nm with an output power
of 102 mW and a bandwidth less than 2 pm when bidirectionally pumped at 976 nm.
The WGL device was stable and operated for 50 hours without degradation. This
demonstration of a high performance WGL opens the possibility for creating a
variety of narrow-linewidth laser designs in bulk glasses.
