| In this dissertation, multimode optical fibers (MMFs) have been studied as a robust and practical platform for nonlinear optics and quantum optics applications, where by experimental investigations and theoretical calculations we present the quantum and nonlinear virtue of MMFs as a versatile tool for future applications.;Our investigations can be summarized in three parts: At first, we have investigated stimulated Raman scattering (SRS) in a long MMF, where more than 20 orders of cascaded Raman peaks have been generated. Observation of beam clean-up despite the highly multimode nature of the fiber and such strong nonlinear interaction despite the large fiber core size are distinguishable results of our work. Next, we have studied four-wave mixing (FWM) via intermodal phase-matching in both step-index and graded-index MMFs (GIMFs). A rigorous and general approach in the theoretical study is presented where some of the commonly used, yet inaccurate approximations are avoided. Experimentally, FWM side-bands with minimal contamination from SRS, and residual pump photons have been generated from quantum vacuum and amplified more than 11 orders of magnitude. Finally, in the last part of this dissertation, we have done a theoretical study of photon-pair generation in a multimode optical fiber (both step-index and GIMF) via intermodal-FWM as a source of state-engineered photon-pairs. |
