Watts-level frequency doubling of a narrow line linearly polarized Raman fiber laser to 589nm

A single-mode, linearly polarized, 1118 nm ytterbium fiber laser was applied to pumping of a short fiber length, polarization-maintaining Raman cavity, resulting in a 0.4 nm linewidth, 23 W CW source at 1179 nm. Efficient, single-pass frequency doubling of the Raman source in MgO doped PPLN to 589 nm was demonstrated with CW power levels in excess of 3 W. No beam quality degradation was observed due to photorefraction at pump power densities up to 2 MW/cm(2). The proposed approach can be readily extended to Watt-level generation of any desired wavelength in the 560 to 770 nm range.