Spatiotemporal Characterization of Supercontinuum Extending from the Visible to the Mid-Infrared in Multimode Graded-Index Optical Fiber

TL;DR

This paper demonstrates the generation of a broad, flat supercontinuum spectrum from visible to mid-infrared in a graded-index multimode fiber using sub-ns laser pulses, with detailed spatiotemporal analysis.

Contribution

It provides the first experimental characterization of supercontinuum extending to 2500 nm in multimode fibers, analyzing the interplay of nonlinear effects and spatiotemporal dynamics.

Findings

Supercontinuum spans from visible to 2500 nm with a flat spectral profile.

The supercontinuum exhibits a uniform bell-shaped spatial beam profile.

Analysis reveals competition between Kerr-induced instability and Raman scattering.

Abstract

We experimentally demonstrate that pumping a graded-index 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.