Raman fiber laser using spectrally shaped multi-wavelength fiber loop mirrors

A two Stokes fiber Raman laser was fabricated for the first time using only two fiber loop mirrors. The laser operates at 1475 nm, the second Stokes order of a P-doped fiber, when pumped at 1060 nm. The entrance loop acts as a pump injector as well as a high-reflector for both Stokes waves, while the exit loop is a high- reflector for the first Stokes wave and an output coupler of R=52% for the second one. The slope efficiency achieved was 12.4% for 600 m of P-doped fiber, with a threshold of 1.2 W for the second Stokes wave.