High-power, low-noise, Yb-doped, cladding-pumped, three-level fiber sources at 980 nm

We present results on a high-power, cladding-pumped, Yb-doped fiber emitting at 977 run in laser and ampllified-spontaneous-emission source configurations. We obtained up to 1.4 W of fiber-coupled, single-mode output power and slope efficiency as high as 68%. To our knowledge these are the highest powers and efficiencies achieved from a single-mode fiber laser at similar to980 nm and the first demonstrated results on a high-power amplified-spontaneous-emission source in this wavelength range. High power and high slope efficiency are achieved by using a high numerical aperture (>0.7), a jacketed air-clad fiber, and a high-brightness pump source. Both types of sources exhibit relative intensity noise below -130 dB/Hz and are thus suitable for a wide range of applications. (C) 2003 Optical Society of America.