Power Fluctuations of Intermodal Four-Wave Mixing in Few-Mode Fibers

We demonstrate the full bandwidth measurement of the intermodal four-wave mixing efficiency for a 4.7-km three-spatial-mode few-mode fiber. Large fluctuations of intermodal four-wave mixing between the LP $_{01}$ and LP$_{11}$ modes are experimentally observed. These fluctuations exhibit a strong wavelength dependence that can be persistent in time. The fluctuations are also shown to display some polarization dependence.