Three-cascaded 1407-nm Raman laser based on phosphorus-doped silica fiber

We report a laser-diode-pumped 1407-nm Raman fiber laser with an output power of 1 W. In this three-cascaded cw Raman laser, based on a single active phosphorus-doped silica fiber, for the first time to the authors’ knowledge successive generation of Stokes components of essentially different frequency shifts (1330 and $490 {\mathrm{cm}}^{-1}$) has been realized. These Stokes components are associated with both constituents (${\mathrm{P}}_2{\mathrm{O}}_5$ and ${\mathrm{SiO}}_2$) of the fiber core glass.