Competition between the Modulation Instability and Stimulated Brillouin Scattering in a Broadband Slow Light Device

TL;DR

This study investigates the competition between modulation instability and stimulated Brillouin scattering in a broadband slow light device using optical fibers, revealing how MI dominance affects SBS performance and delay.

Contribution

It demonstrates the impact of MI on SBS slow light devices and compares performance in standard and dispersion-shifted fibers, highlighting the suppression of MI to enhance SBS delay.

Findings

MI dominates in LEAF fiber, reducing SBS gain and delay.

SBS gain-bandwidth limited to 126 dB·GHz in LEAF fiber.

Improved SBS delay and gain-bandwidth in dispersion-shifted fiber.

Abstract

We observe competition between the modulation instability (MI) and stimulated Brillouin scattering (SBS) in a 9.2-GHz broadband SBS slow light device, in which a standard 20-km-long single-mode LEAF fibre is used as the SBS medium. We find that MI is dominant and depletes most of the pump power when we use an intense pump beam at ~1.55 {\mu}m, where the LEAF fibre is anomalously dispersive. The dominance of the MI in the LEAF-fibre-based system suppresses the SBS gain, degrading the SBS slow light delay and limiting the SBS gain-bandwidth to 126 dB \cdot GHz. In a dispersion-shifted highly nonlinear fibre, the SBS slow light delay is improved due to the suppression of the MI, resulting in a gain-bandwidth product of 344 dB \cdot GHz, limited by our available pump power of 0.82 W.