Spatiotemporal characterization of supercontinuum extending from the visible to the mid-infrared in a multimode graded-index optical fiber

We experimentally demonstrate that pumping a gradedindex
multimode fiber with sub-ns pulses from a microchip
Nd:YAG laser leads to spectrally flat supercontinuum
generation with a uniform bell-shaped spatial beam profile
extending from the visible to the mid-infrared at 2500 nm.
We study the development of the supercontinuum along
the multimode fiber by the cut-back method, which permits
us to analyze the competition between the Kerr-induced
geometric parametric instability and stimulated Raman
scattering. We also performed a spectrally resolved temporal
analysis of the supercontinuum emission.