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Measurement of the anomalous phase velocity of ballistic light in a random medium by use of a novel interferometer

Yang, Changhuei and Wax, Adam and Feld, Michael S. (2000) Measurement of the anomalous phase velocity of ballistic light in a random medium by use of a novel interferometer. Optics Letters, 26 (4). pp. 235-237. ISSN 0146-9592. http://resolver.caltech.edu/CaltechAUTHORS:YANol01a

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Abstract

Ballistic light, i.e., radiation that propagates undeflected through a turbid medium, undergoes a small change in phase velocity and exhibits unusual dispersion because of its wave nature. We use a novel highly sensitive differential phase optical interferometer to study these previously unmeasurable phenomena. We find that ballistic propagation can be classified into three regimes based on the wavelength-to-size ratio. In the regime in which the scatterer size is comparable with the wavelength, there is an anomalous phase-velocity increase as a result of adding scatterers of higher refractive index. We also observe an anomaly in the relative phase velocity, where red light is slowed more than blue light even though the added scatterers are made of material with normal dispersion.


Item Type:Article
Additional Information:© 2001 Optical Society of America Received September 11, 2000 We acknowledge valuable suggestions from Arjun Yodh of the University of Pennsylvania. We also thank Lev T. Perelman and Ramachandra R. Dasari for useful discussions. This work was carried out at the Massachusetts Institute of Technology Biomedical Research Center and was supported by National Institutes of Health (NIH) grant P41-RR02594 and a grant from the Hamamatsu Corporation. A. Wax was supported by a National Research Service Award from the NIH (grant 1 F32 RR05075-01).
Funders:
Funding AgencyGrant Number
NIHP41-RR02594-18
Hamamatsu CorporationUNSPECIFIED
NIH Postdoctoral Fellowship1 F32 RR05075-01
Subject Keywords:Coherence; Interferometry; Phase measurement
Issue or Number:4
Record Number:CaltechAUTHORS:YANol01a
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:YANol01a
Alternative URL:http://www.opticsinfobase.org/abstract.cfm?URI=ol-26-4-235
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3327
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:30 May 2006
Last Modified:13 Mar 2017 22:15

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