Investigation of nonlinear effects in few-mode fibers

In this work, nonlinear optical effects are exploited for future implementations of space-division multiplexing fiber systems. The paper first presents the fundamentals of intermodal nonlinear phenomena over few-mode fibers, such as cross-phase modulation, four-wave mixing (FWM), stimulated Brillouin scattering and stimulated Raman scattering. Second, the potential applications of few-mode nonlinear effects are discussed for sensing and optical signal processing. We demonstrated how fiber mode symmetries and linear mode coupling affect intermodal power transfer and spectral broadening. Lastly, the paper proposes a ultrafast all-optical simultaneous wavelength and mode conversion scheme based on intermodal FWM, with the capability of switching state of polarization and mode degeneracy orientation. Under this scheme, cross-polarization modulation and cross-mode modulation can be achieved.