Low Spontaneous Brillouin Scattering in Anti-Resonant Hollow-Core Fibers in GHz Frequency Range

TL;DR

This study demonstrates that anti-resonant hollow-core fibers significantly reduce spontaneous Brillouin scattering compared to conventional fibers, making them ideal for low-noise BLS experiments in the GHz range.

Contribution

The paper introduces the use of anti-resonant hollow-core fibers for BLS, showing their superior performance in minimizing spontaneous scattering relative to traditional solid-core fibers.

Findings

Hollow-core fibers exhibit much lower spontaneous BLS signals than solid-core fibers.

Finite-element simulations link phononic modes to specific acoustic structures.

Anti-resonant hollow-core fibers are promising for low-noise photonic applications.

Abstract

Brillouin light scattering (BLS) is a powerful experimental tool that can be used to get insights into the fundamental and applied properties of matter, like dispersions of quasiparticles in a solid, as well as their spatio-temporal dynamics. Many applications of light scattering favor the use of optical fibers in place of free-space optics. In this work, we compare the performance of anti-resonant hollow core fibers to that of conventional solid core fused silica fibers for BLS experiments in the GHz frequency range. Conventional fibers are barely suitable for low-noise measurements because of the spontaneous scattering of the photons on various phononic modes present in the core and cladding. In the case of the hollow-core fiber, we identify a range of discrete phononic modes and associate them with the various acoustic modes of the structure surrounding the hollow core using finite-element numerical simulations. The measured relative intensity of the spontaneous BLS signal from these modes is orders of magnitude smaller than that of a solid-core fiber, making anti-resonant hollow-core fibers one of the best solutions for the single-mode light guidance for BLS and potentially other low-noise photonic experiments.