A light source includes a wavelength shifter that is capable of shifting a shorter optical signal wavelength to a longer optical signal wavelength based at least in part on a Raman effect in a waveguide. The wavelength shifter includes a pump laser that operable to produce the shorter optical signal wavelength. The wavelength shifter also includes an intermediate stage that is coupled to the pump laser and capable of producing an intermediate optical signal wavelength. The intermediate optical signal wavelength is longer than the shorter optical signal wavelength. The wavelength shifter further includes a final stage capable of generating the longer optical signal wavelength. The final stage includes at least in part a ZBLAN waveguide and wherein the longer optical signal wavelength is greater than 1.7 microns and is greater than the intermediate pump signal wavelength.