Extended continuous-wave supercontinuum generation in a low-water-loss holey fiber

We report on the development of a $2.5\mu \mathrm{m}$ core photonic crystal fiber with a substantially reduced water-peak loss around $1.38\mu \mathrm{m}$, which allows extended Raman-soliton supercontinuum generation up to $1.55\mu \mathrm{m}$ with a cw ytterbium fiber laser pump source. The resulting broadband, high-spectral-power-density, low-coherence light source can be employed for advanced, submicrometer resolution optical coherence tomography.