Silica-based fiber Raman laser at > 2.4 μm

Raman laser generation at the long wavelength transmission edge of silica fiber is explored. Numerical simulation reveals that high efficiency 2nd Stokes Raman laser operation around 2.5 mu m is feasible with highly Ge-doped silica fiber as the gain medium and pulsed 2-mu m fiber laser as the pump source. Based on the spontaneous cascaded Raman amplification process, 0.30-W laser at 2.43 mu m is obtained with an optical efficiency of 16.5% pumped at 2008 nm. And 0.15-W laser at 2.48 mu m is achieved with an optical efficiency of 7.9% pumped at 2040 nm. To the best of our knowledge, the results represent the longest wavelength operation of silica-based fiber laser. (C) 2015 Optical Society of America