Pathlengths of open channels in multiple scattering media

TL;DR

This study demonstrates that open transmission channels in three-dimensional diffusive media have significantly wider spectral widths than previously observed in localized regimes, achieved through digital optical phase conjugation.

Contribution

It introduces a method to measure and enhance open channel transmission in diffusive media, revealing their broader spectral properties.

Findings

Enhanced transmission correlates with increased spectral width of the field correlation function.

Open channels in diffusive media are spectrally wider than in localized regimes.

Transmission enhancement persists over a larger frequency bandwidth.

Abstract

We report optical measurements of the spectral width of open transmission channels in a three-dimensional diffusive medium. The light transmission through a sample is enhanced by efficiently coupling to open transmission channels using repeated digital optical phase conjugation. The spectral properties are investigated by enhancing the transmission, fixing the incident wavefront and scanning the wavelength of the laser. We measure the transmitted field to extract the field correlation function and the enhancement of the total transmission. We find that optimizing the total transmission leads to a significant increase in the frequency width of the field correlation function. Additionally we find that the enhanced transmission persists over an even larger frequency bandwidth. This result shows open channels in the diffusive regime are spectrally much wider than previous measurements in the localized regime suggest.