An infrared light source includes one or more combiners that are coupled to at least a first pump laser and a second pump laser. The combiners are operable to couple a first optical signal generated by the first pump laser and a second optical signal generated by the second pump laser to a gain fiber, the gain fiber comprising a first waveguide structure. The light source also includes a Raman wavelength shifter that is coupled to the gain fiber. The Raman wavelength shifter being operable to wavelength shift based at least in part on a Raman effect. At least a portion of the Raman wavelength shifter comprising an intermediate waveguide structure that is coupled to a second waveguide structure capable of wavelength shifting at least one wavelength of the first optical signal to an intermediate wavelength in the intermediate waveguide structure and then a longer signal wavelength in the second waveguide structure.