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Proceedings Paper

Biophotonic applications of eigenchannels in a scattering medium (Conference Presentation)
Author(s): Moonseok Kim; Wonjun Choi; Youngwoon Choi; Changhyeong Yoon; Wonshik Choi
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Paper Abstract

When waves travel through disordered media such as ground glass and skin tissues, they are scattered multiple times. Most of the incoming energy bounces back at the superficial layers and only a small fraction can penetrate deep inside. This has been a limiting factor for the working depth of various optical techniques. We present a systematic method to enhance wave penetration to the scattering media. Specifically, we measured the reflection matrix of a disordered medium with wide angular coverage for each orthogonal polarization states. From the reflection matrix, we identified reflection eigenchannels of the medium, and shaped the incident wave into the reflection eigenchannel with smallest eigenvalue, which we call anti-reflection mode. This makes reflectance reduced and wave penetration increased as a result of the energy conservation. We demonstrated transmission enhancement by more than a factor of 3 by the coupling of the incident waves to the anti-reflection modes. Based on the uneven distribution of eigenvalues of reflection eigenchannels, we further developed an iterative feedback control method for finding and coupling light to anti-reflection modes. Since this adaptive control method can keep up with sample perturbation, it promotes the applicability of exploiting reflection eigenchannels. Our approach of delivering light deep into the scattering media will contribute to enhancing the sensitivity of detecting objects hidden under scattering layers, which is universal problem ranging from geology to life science.

Paper Details

Date Published: 27 April 2016
PDF: 1 pages
Proc. SPIE 9717, Adaptive Optics and Wavefront Control for Biological Systems II, 97170R (27 April 2016); doi: 10.1117/12.2213169
Show Author Affiliations
Moonseok Kim, Wellman Ctr. for Photomedicine, Massachusetts General Hospital (United States)
Harvard Medical School (United States)
Wonjun Choi, Univ. of Exeter (United Kingdom)
Youngwoon Choi, Korea Univ. (Korea, Republic of)
Changhyeong Yoon, Korea Univ. (Korea, Republic of)
Wonshik Choi, Korea Univ. (Korea, Republic of)

Published in SPIE Proceedings Vol. 9717:
Adaptive Optics and Wavefront Control for Biological Systems II
Thomas G. Bifano; Joel Kubby; Sylvain Gigan, Editor(s)

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