Ultrawide-range four-wave mixing in Raman distributed-feedback fiber lasers

We report ultrawide-range and highly efficient wavelength conversion by exploiting four-wave mixing (FWM) in Raman distributed-feedback (R-DFB) fiber lasers. The lasers are 30 cm long center pi phase-shifted DFB gratings UV written in commercially available germano-silica (Ge/Si) single-mode fibers (PS980 from Fibercore Ltd., and UHNA4 from Nufern). The R-DFB lasing signal acts as a pump wave for the FWM process within the DFB cavity, and the obtained FWM conversion efficiency is around -25 dB with a maximum wavelength conversion range of 112 nm