Polarization Control in Closed Cavity Raman Fiber Lasers

We present an experimental study of the polarization properties of Raman lasers based on a closed cavity configuration with highly polarized pumps, using different fiber gain media ranging from low-polarization mode dispersion (PMD) single mode fiber to high-PMD dispersion compensation fiber (DCF). The output spectrum, output degree of polarization (DOP) and state of polarization (SOP) evolution of the generated first Stokes component in both propagation directions is investigated for varying pump SOP. Our findings expose a remarkable improvement in pumping efficiency and output DOP even in the worst-case scenario of a cavity encompassing a high-PMD fiber.