Hybrid fiber Raman-bismuth amplifier pumped by semiconductor disk laser operating at 1.3 μm

We present a hybrid Raman-bismuth fiber amplifier pumped in co-propagation configuration by a single 1.22 μm semiconductor disk laser. The unique feature of this dual-gain system is that both amplifiers require the pump source with the same wavelength because pump-Stokes spectral shift in 1.3 μm Raman amplifier and pump-gain bandwidth separation in 1.3 μm bismuth fiber amplifier have the same value. Residual pump power at the output of Raman amplifier in this scheme is efficiently consumed by bismuth-doped fiber thus increasing the overall conversion efficiency. The small-signal gain of 18 dB at 1.3 W of pump power has been achieved for hybrid scheme which is by 9 dB higher as compared with isolated Raman amplifier without bismuth fiber. Low noise performance of pump semiconductor disk laser with RIN of -150 dB/Hz combined with nearly diffraction-limited beam quality and Watt-level output powers allows for efficient core-pumping of a single-mode fiber amplifier system and opens up new opportunities for amplification in O-band spectral range.