Untangled Brillouin light scattering for mechanical imaging in turbid samples

Brillouin microscopy is a label-free and noncontact optical method to measure fundamental viscoelastic properties of biological systems. One of the main challenges in Brillouin microscopy is given by the strong Rayleigh background light overcoming the Brillouin peaks that are spectrally located at a few GHz from the laser frequency. Here, we demonstrate a common-path and broadband notch filter providing an unprecedented 65 dB extinction ratio. We demonstrate the filter by acquiring Brillouin spectra of highly turbid samples, such as pure milk and unprocessed vertebra bone tissues.