High power operation of an ytterbium-doped multi-core ribbon fiber laser and a cladding pumped ytterbium-doped
helical core fiber laser is reported. 320W laser output at 1045nm was demonstrated with a 10-core ytterbium doped
ribbon fibre. Efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser with a 30
μm diameter core and a numerical aperture of 0.087 have also been demonstrated. The laser yielded 60.4 W of output at
1043 nm in a beam with M<sup>2</sup> 1.4 for 92.6 W launched pump power from a diode stack at 976 nm. Further more, the
recently progress of a cladding-pumped ytterbium-doped helical-core superfluorescent fiber source is also reported. The
highly efficient operation of the helical core fiber ASE source yielded 107W of amplified spontaneous emission output
spanning the wavelength range from 1030-1160nm with a bandwidth (FWHM) of 37nm.
An efficient double-clad erbium-ytterbium co-doped fiber laser pumped by two high-power diode-stacks at 975nm is reported. Using a simple external cavity configuration at one end of the fiber and the 3.6% Fresnel reflection from a cleaved fiber end facet at the opposite end of the fiber to provide the necessary feedback for lasing, we obtained a maximum output power of 159W at 1565nm in a beam with beam quality factor (M<sup>2</sup>) ~1.9 for 466W of launched pump power. The corresponding slope efficiency with respect to launched pump power was 34%. The maximum output power was limited by the available pump power. A strategy for increasing the output power and improving the beam quality based on the use of a double-clad fiber design with a helical-core trajectory is considered.