Numerical Insights into noise amplification of high-energy mid-infrared supercontinuum generation in normal dispersion multimode fibers

TL;DR

This paper investigates the noise amplification mechanisms in high-energy mid-infrared supercontinuum generation within multimode fibers, highlighting the role of stimulated Raman scattering and the importance of pump noise control for low-noise output.

Contribution

It provides a numerical analysis of noise dynamics in MIR supercontinuum generation, emphasizing the impact of pump noise and the conditions for minimizing noise amplification.

Findings

Stimulated Raman scattering causes significant noise amplification.

Increasing pump noise shortens coherence length and worsens incoherent broadening.

Using short-pulse, low-noise pumping improves supercontinuum coherence.

Abstract

We report on the noise properties of high-energy mid-infrared supercontinuum (MIR-SC) generation in normal dispersion multimode fibers from the numerical perspective. Noise amplification in multi-modes is primarily due to the stimulated Raman scattering (SRS) effect. This leads to the emergence of "incoherent cloud formation" and "incoherent optical wave breaking", similar to those observed in single-mode fibers. Increasing the pump technical noise from 0.1 % to 1 % significantly shortens the lumped coherence length L_C and exacerbates the influence of incoherent broadening dynamics competing with coherent dynamics, resulting in MIR-SC being a strong consistency in the collapse evolution of amplitude noise and phase coherence. To minimize this noise amplification and achieve high-energy low-noise MIR-SC in practical applications, it is essential to use short-pulse pumping with low amplitude noise, ensuring that L_C>>L_OWB (where L_OWB denotes the optical wave breaking length).