Frequency-Resolved Spatial Beam Mapping in Multimode Fibers: Application to Mid-Infrared Supercontinuum Generation

TL;DR

This paper introduces a novel spatial-spectral mapping technique for detailed beam analysis in multimode fibers, enabling visualization of beam structures and facilitating supercontinuum generation in the mid-infrared range.

Contribution

A new spatial-spectral mapping method is developed for high-resolution beam characterization in multimode fibers, aiding in the study and enhancement of supercontinuum generation.

Findings

Successfully visualized the beam structure of GPI sidebands at 1870 nm.

Achieved supercontinuum spanning from 1.7 μm to 3.4 μm.

Demonstrated amplification and spectral broadening of GPI sidebands.

Abstract

We present a new spatial-spectral mapping technique permitting to measure the beam intensity at the output of a graded-index (GRIN) multimode fiber with sub-nanometric spectral resolution. We apply this method to visualize the fine structure of the beam shape of a sideband generated at 1870 nm by geometric parametric instability (GPI) in a GRIN fiber. After spatial-spectral characterization, we amplify the GPI sideband with a Tm-doped fiber amplifier to obtain a microjoule-scale picosecond pump whose spectrum is finally broadened in a segment of InF3 optical fiber to achieve supercontinuum ranging from 1.7 {\mu}m up to 3.4 {\mu}m