Fig. 4 : Cascaded Raman scattering for wavelength conversion across 2-5 μm.

a Simulated spectral evolution of cascaded Raman scattering with 2 μm pulsed laser pump. b Output peak powers of Stokes waves as a function of fiber length for Fig. 4a. c Simulated spectral evolution with 2.2 μm pulsed laser pump. d Output Stokes peak powers as a function of fiber length for Fig. 4c