Performance studies of directly written high power monolithic ytterbium waveguide oscillators

The paper introduces femtosecond laser direct write technique, that does nor require a lithographic mask, and is readily available with existing fiber system. This technique has been successfully used to fabricate monolithic distributed feedback (DFB) waveguide oscillator devices. An efficient, high-power waveguide laser (WGL) operating at 1.032 mum was recently fabricated in ytterbium-doped phosphate glass with single-ended output powers over 100 mW. The pump power threshold was approximately 115 mW and the optical efficiency was over 17%. This WGL typically operated on two degenerate polarisation modes but could be restricted to a single- polarisation mode through the use of polarised pump light.