Towards visible CW pumped supercontinua

We report a 1 um continuous wave pumped supercontinuum which extends short of the pump wavelength to 0.65 um. This is achieved by using a 50 W Yb fibre laser in combination with a photonic crystal fibre with a carefully engineered zero dispersion wavelength. We show that the short wavelength generation is due to a combination of four-wave mixing and dispersive wave trapping by solitons. The evolution and limiting factors of the continuum are discussed.