Optimized virtual optical waveguides enhance light throughput in scattering media

Adithya Pediredla*, Matteo Giuseppe Scopelliti*, Srinivasa Narasimhan, Maysamreza Chamanzar, Ioannis Gkioulekas

Nature Communications 2023

teaser
Left: Ultrasonically-sculpted gradient-index virtual optical waveguides enable light confinement and focusing inside tissue. Middle: We develop a physics-based rendering algorithm that simulates continuous refraction and multiple scattering of light paths inside such waveguides. We use this simulator to quantify the impact of ultrasound and medium optical parameters on light confinement level. Right: Using our simulator, we configure virtual optical waveguides that enhance light throughput by 50% compared to an ideal external lens, in a medium with bladder-like optical properties at one transport mean free path.

Abstract

Ultrasonically-sculpted gradient-index optical waveguides enable non-invasive light confinement inside scattering media. The confinement level strongly depends on ultrasound parameters (e.g., amplitude, frequency), and medium optical properties (e.g., extinction coefficient). We develop a physically-accurate simulator, and use it to quantify these dependencies for a radially-symmetric virtual optical waveguide. Our analysis provides insights for optimizing virtual optical waveguides for given applications. We leverage these insights to configure virtual optical waveguides that improve light confinement fourfold compared to previous configurations at five mean free paths. We show that virtual optical waveguides enhance light throughput by 50% compared to an ideal external lens, in a medium with bladder-like optical properties at one transport mean free path. We corroborate these simulation findings with real experiments: we demonstrate, for the first time, that virtual optical waveguides recycle scattered light, and enhance light throughput by 15% compared to an external lens at five transport mean free paths.

Experiments

experiments
Experimental setup schematic and comparison between real data and simulated data. Left: Photograph of our setup. Middle: Ray diagrams for two focusing configurations we capture data for. Right: Comparisons between measured and simulated data.

Resources

Paper: Our paper is available on Nature and locally.

Code: Our code is available on Zenodo.

Data: The data to reproduce our experiments is available on Zenodo.

Citation

@article{Pediredla:US:2023,
	title={Optimized virtual optical waveguides enhance light throughput in scattering media},
	author={Pediredla, Adithya and Scopelliti, Matteo Giuseppe and Narasimhan, Srinivasa and Chamanzar, Maysamreza and Gkioulekas, Ioannis},
	journal={Nature Communications},
	volume={14},
	number={1},
	pages={5681},
	year={2023},
	publisher={Nature Publishing Group}
}

Acknowledgments

This work was supported by NSF Expeditions award 1730147, NSF awards 1900849 and 1935849, a gift from AWS Cloud Credits for Research, a gift from the Sybiel Berkman Foundation, a Sloan Research Fellowship for Ioannis Gkioulekas, and James Sprague Presidential Graduate Fellowship for Matteo Scopelliti.