Dispersive coherent Brillouin scattering spectroscopy

TL;DR

This paper introduces a novel dispersive coherent Brillouin scattering spectroscopy technique that combines time- and frequency-domain methods, enabling multichannel detection and significantly faster signal acquisition for real-time mechanical imaging.

Contribution

It presents a new spectroscopic approach that enhances Brillouin scattering measurements by integrating dispersive techniques for improved speed and multichannel capabilities.

Findings

Achieved at least 100-fold increase in signal acquisition speed.

Successfully imaged heterogeneous thin films and biological cells.

Demonstrated nanometer depth resolution in imaging applications.

Abstract

Frequency- and time-domain Brillouin scattering spectroscopy are powerful tools to read out the mechanical properties of complex systems in material and life sciences. Indeed, coherent acoustic phonons in the time-domain method offer superior depth resolution and a stronger signal than incoherent acoustic phonons in the frequency-domain method. However, it does not allow multichannel detection and, therefore, falls short in signal acquisition speed. Here, we present Brillouin scattering spectroscopy that spans the time and frequency domains to allow the multichannel detection of Brillouin scattering light from coherent acoustic phonons. Our technique maps the time-evolve Brillouin oscillations at the instantaneous frequency of a chromatic-dispersed laser pulse. The spectroscopic heterodyning of Brillouin oscillations in the frequency domain enhances the signal acquisition speed by at least 100-fold over the time-domain method. As a proof of concept, we imaged heterogeneous thin films and biological cells over a wide bandwidth with nanometer depth resolution. We, therefore, foresee that our approach catalyzes future phonon spectroscopy toward real-time mechanical imaging.