High-Power Narrow-Linewidth Continuous-Wave Raman Amplifier at 1.27 $\mu$ m

A high-power narrow-linewidth continuous-wave (CW) Raman fiber amplifier at 1.27 μm is demonstrated for remote sensing measurements of atmospheric oxygen (O
₂
). The amplifier uses phosphosilicate fiber in both a standard single-mode design and with the core size varying in the longitudinal direction for stimulated Brillouin scattering (SBS) suppression. The highest reported power level at this wavelength to date, a total peak power of 3 W, has been achieved for online (2.4 W) and offline (580 mW) spectroscopic measurements, in agreement with theoretical predictions. Additionally, it is shown that when 60-kHz sinusoidal amplitude modulation is applied to the amplifier seed signal, the modulated wave form is preserved at the amplifier output with 1.8 W total average power being obtained.