Embodiments of the present invention generally relate to optical mode conversion by nonlinear effects. More specifically, embodiments of the present invention relate to nonlinear mode conversion utilizing intermodal four-wave mixing to convert light between modes having different wavelengths for complex applications. In one embodiment of the present invention, a fiber comprises an input end for receiving light in a first mode at a first wavelength, and an output end for outputting light in a desired second mode at a desired second wavelength, wherein the first wavelength and the second wavelength are not the same. In many embodiments, the fiber comprises a higher-order mode fiber.