Vortex-Structured-Light-Assisted High-Contrast Brillouin Spectroscopy

Brillouin spectroscopy has emerged as a promising nondestructive and label-free imaging tool in the field of mechanobiology, enabling the acquisition of fundamental viscoelastic information conveyed by the acoustic vibrations of matter. While the feasibility and potential of this innovative technique have been extensively demonstrated, Brillouin spectroscopy still faces challenges at interfaces with different refractive indices and in turbid samples where strong background elastic light can overwhelm the signal. In this study, we present a high-contrast Brillouin scattering method that uses vortex-structured light generated by a liquid-crystal polymer (LCP) waveplate, which achieves an additional background rejection ratio exceeding 30 dB. We also employ this method in collecting Brillouin spectra in extremely scattering environments and across highly reflective interfaces. Our method offers a simple and cost-effective way to improve the signal-to-noise ratio (SNR) in Brillouin spectroscopy, with potential applications in mechanobiology scenarios.