Controlling light propagation in multimode fibers

A multimode optical fiber subjected to random mode and polarization mixing represents a complex photonic system with strong coupling of spatial, temporal, spectral and polarization degrees of freedom. By exploiting such coupling, we demonstrate a full control of the temporal shape and polarization state of light transmitted through a multimode fiber by adjusting the spatial profile of incident field. Furthermore, we show that a multi-mode fiber can function as a high-resolution, low-loss spectrometer. The frequency-dependent speckle patterns are used for spectrum recovery. We have made a multimode fiber spectrometer with ultra-fine resolution, and applied it to optical frequency comb spectroscopy.