arXiv subjects

Zixuan Du

Publications and source records attributed to Zixuan Du.

3 recordsLinked to original sources

arXiv2026

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

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.

physics.optics↗

arXiv2025

Pulsed heterodyne Brillouin detection enables high-resolution epi-detected biomechanical microscopy and endoscopy

Brillouin microscopy enables non-contact, three-dimensional mapping of viscoelasticity in living systems, yet two long-standing limitations have constrained its biological reach: the lack of high-spectral-resolution epi-detection and the absence of practical fiber-compatible implementations. Here we introduce pulsed heterodyne Brillouin detection (PHBD), a coherent time-domain scheme addressing both challenges. By combining high-peak-power pulsed excitation with shot-noise-limited detection, PHBD reduces the optical dose by approximately two orders of magnitude relative to continuous-wave heterodyne approaches. In an epi-microscope configuration, PHBD attains a spectral resolution of 27 MHz, a tenfold improvement over state-of-the-art Brillouin microscopes, enabling high-specificity, low-phototoxicity imaging of live cells and complex tissues. In an endoscopic configuration, coherent gating rejects parasitic Brillouin background from the delivery fiber, accelerating acquisition by two to three orders of magnitude over previous fiber-optic Brillouin endoscopes. Together, these capabilities establish a unified platform for single-ended, fiber-compatible Brillouin biomechanics, extending mechanical imaging and spectroscopy from cells to deep tissues via minimally invasive probes.

physics.optics↗

arXiv2025

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

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.

physics.optics↗