Simultaneous operation of a Raman fiber amplifier and laser pumped by a dual-wavelength Nd3+-doped fiber laser

This paper presents an experimental study on the dynamics of Raman fiber lasers that use highly GeO₂-doped fibers as an active medium and a dual-wavelength (1060 and 1090 nm) Nd³⁺-doped fiber laser as a pump source. The 1090-nm pump wavelength is located within the SiO₂ Raman gain spectrum relating to the 1060-nm pump wavelength, and competition is observed between Raman amplification of the 1090-nm emission with the 1060-nm emission used as the pump source and Raman lasing, which is independent of the 1090-nm amplification and which is also uses the 1060-nm emission as the pump source. Several pump configurations have been demonstrated to generate specific Stokes emissions generated through Raman lasing or amplification. Changing the gain-to-loss ratio by introducing intracavity loss of Raman emissions or increasing the Raman fiber length within each configuration can force either Raman amplification or lasing to dominate. The maximum slope efficiency as a function of the launched pump power was ∼55% with a total output power of 1.6 W produced. A red shift of both the pump and the Stokes wavelengths is experimentally observed when the launched diode pump power is scaled up.