Third order cascaded Raman wavelength shifting in chalcogenide fibers and determination of Raman gain coefficient

Cascaded Raman wavelength shifting up to three orders from 1553 nm to 1867 nm is demonstrated in As₂S₃-chalcogenide fibers. Due to a long zero dispersion wavelength for the sulfide fiber (>4.5 μm), pumping the fiber at 1553 nm results in generation of cascaded Stokes orders based on stimulated Raman scattering. Using the threshold power for the Raman orders, we estimate the Raman gain coefficient for the As₂S₃ fibers to be ∼5.7×10^-12 m/W at 1550 nm. Observation of higher Raman orders is limited by damage to the fiber at input intensities >1 GW/cm².