Spatiotemporal light-beam compression from nonlinear mode coupling

TL;DR

This paper demonstrates simultaneous spatial and temporal compression of light pulses in multimode nonlinear fibers, revealing new insights into mode coupling and pulse reshaping effects.

Contribution

It introduces experimental evidence of combined spatial and temporal compression in multimode fibers and explores nonlinear mode dynamics within a single pulse.

Findings

Up to four-fold shortening of laser pulses.

Significant spatial beam self-cleaning observed.

Nonlinear mode coupling depends on instantaneous power.

Abstract

We experimentally demonstrate simultaneous spatial and temporal compression in the propagation of light pulses in multimode nonlinear optical fibers. We reveal that the spatial beam self-cleaning recently discovered in graded-index multimode fibers is accompanied by significant temporal reshaping and up to four-fold shortening of the injected sub-nanosecond laser pulses. Since the nonlinear coupling among the modes strongly depends on the instantaneous power, we explore the entire range of the nonlinear dynamics with a single optical pulse, where the optical power is continuously varied across the pulse profile.