Enhanced Efficiency of Multiple Four-Wave Mixing Induced by Modulation Instability in Low-Birefringence Fibers

Modulation instability (MI) induced by two strong beams and a weak beam via cross phase modulation is investigated. Multiple four-wave-mixing (FWM) processes associated with the MI in low-birefringence fibers are studied both theoretically and experimentally. The coupled-mode equations describing the MI-induced FWM nonlinear interactions between pump waves and sideband waves are derived. Theoretical and experimental results show that, on the assistance of MI, new optical frequencies can be generated quite efficiently from multiple FWM processes. More than eleven sidebands are experimentally achieved by the MI-driven multiple FWM processes. The transfer of energy from pumps to sidebands can be dramatically enhanced by the MI-induced parametric process. The experimental observations by using a piece of highly nonlinear dispersion-flattened photonic-crystal fiber confirm our theoretical predictions.