Frequency shifting of light via multiple ultrasound waves in scattering media

TL;DR

This paper develops an analytical model for light frequency shifting in scattering media caused by ultrasound, validated by simulations, and explores optimization of ultrasound parameters for improved efficiency in biomedical optical applications.

Contribution

It introduces a comprehensive analytical framework for understanding and optimizing ultrasound-induced light frequency shifts in scattering media, including multiple ultrasound waves and high-pressure regimes.

Findings

Analytical expressions accurately predict frequency shifts.

Model validated through Monte Carlo simulations.

Insights into ultrasound parameter optimization for enhanced efficiency.

Abstract

We derive analytical expressions to describe how light is frequency-shifted when interacting with ultrasound within scattering media, due to the modulation of the refractive index induced by the ultrasound pressure waves. The model is validated through Monte Carlo simulations, works for high ultrasound pressures, and allows for many simultaneous ultrasound waves or frequency components, which is important due to the non-linear propagation effects in tissue. We also provide critical insights into how the ultrasound properties can be optimized for an enhanced efficiency of the light to be frequency-shifted, facilitating applications in ultrasound optical tomography and other photonic diagnostic techniques.