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arXiv · 2603.07097

Impact of refractive index heterogeneity on stimulated Brillouin scattering microscopy: a quantitative analysis

Meng Xu·Zixuan Du·Yun Qi·Jinrui Zhang·Shuai Yao·Robert Prevedel·Fan Yang
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Abstract

Stimulated Brillouin scattering (SBS) microscopy enables label-free biomechanical imaging, with Brillouin gain serving as a critical contrast parameter for quantitative analysis. However, the influence of sample-induced refractive index (RI) heterogeneity on gain measurements remains poorly understood. Here, we quantitatively investigate, how RI mismatch affects SBS microscopy using finite element simulations and experiments on a phantom sample comprising polydimethylsiloxane beads embedded in agarose gel. We demonstrate that RI heterogeneity induces focal field distortion that reduce pump-probe beam overlap, resulting in attenuated Brillouin gain and degraded shift precision at material interfaces. Crucially, we establish that fiber-coupling efficiency, commonly used for system alignment, cannot serve as a linear proxy for Brillouin gain due to its heightened sensitivity to focal field distortion.

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Meng Xu, Zixuan Du, Yun Qi, Jinrui Zhang, Shuai Yao, Robert Prevedel, Fan Yang. 2026-03-07. Impact of refractive index heterogeneity on stimulated Brillouin scattering microscopy: a quantitative analysis. https://doi.org/10.1364/ol.591843

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