Focusing of light energy inside a scattering medium by controlling the time-gated multiple light scattering

TL;DR

This paper introduces a method to focus multiple-scattered light waves inside a scattering medium by controlling the time-gated reflection eigenchannels, significantly improving deep light energy delivery for imaging and stimulation.

Contribution

The study presents an experimental technique to counteract wave diffusion and focus scattered waves at specific depths, enhancing energy delivery beyond traditional limits.

Findings

Over 10-fold increase in light energy delivery to deep targets

Effective focusing of multiple-scattered waves at specific flight times

Potential to improve deep imaging and sensing capabilities

Abstract

The efficient delivery of light energy is a prerequisite for non-invasive imaging and stimulating of target objects embedded deep within a scattering medium. However, injected waves experience random diffusion by multiple light scattering, and only a small fraction reaches the target object. Here we present a method to counteract wave diffusion and to focus multiplescattered waves to the deeply embedded target. To realize this, we experimentally inject light to the reflection eigenchannels of a specific flight time where most of the multiple-scattered waves have interacted with the target object and maximize the intensity of the returning multiple-scattered waves at the selected time. For targets that are too deep to be visible by optical imaging, we demonstrated a more than 10-fold enhancement in light energy delivery in comparison with ordinary wave diffusion cases. This work will lay a foundation for enhancing the working depth of imaging, sensing, and light stimulation.