A Framework for Spontaneous Brillouin Noise: Unveiling Fundamental Limits in Brillouin Metrology

TL;DR

This paper develops and experimentally validates a comprehensive framework revealing spontaneous Brillouin scattering noise as a fundamental limit in Brillouin metrology, surpassing traditional noise sources and impacting various sensing and imaging technologies.

Contribution

It introduces the first analytical model predicting spontaneous Brillouin scattering noise as a universal fundamental limit in Brillouin systems, supported by experimental validation.

Findings

SpBS noise can dominate over shot noise in Brillouin metrology.

Experimental demonstration of SpBS-noise-limited regime in imaging and sensing.

Framework provides a basis for optimizing Brillouin technology performance.

Abstract

Spontaneous Brillouin scattering (SpBS) provides a non-contact tool for probing the mechanical and thermodynamic properties of materials, enabling important applications such as distributed optical fiber sensing and high-resolution Brillouin microscopy. Achieving metrological precision in these systems relies critically on identifying fundamental noise sources. While a pioneering study three decades ago numerically investigated an intrinsic SpBS noise mechanism, this phenomenon has remained largely unexplored, particularly in the context of Brillouin metrological systems. Here, by revisiting its physical formation process and rethinking its stochastic behaviors, we develop and experimentally validate a comprehensive analytical framework on this long-overlooked noise source. Importantly, we theoretically predict, for the first time, the SpBS noise is a universal and fundamental limit that can dominate over conventional limits such as shot noise in Brillouin metrological systems like imaging, microscopy and sensing. Specifically, we experimentally demonstrate the SpBS-noise-limited regime in Brillouin imaging and sensing scenarios. This framework establishes a critical foundation for understanding and optimizing the performance bounds of current and future Brillouin-based technologies across diverse applications.