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Proceedings Paper

Influence of the refractive index of liquids in the speckle pattern of multimode fibers
Author(s): Carlos Galindez; Mauro Lomer; Luis Rodriguez-Cobo; J. M. Lopez-Higuera
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Paper Abstract

The distribution of the intensity of each speckle depends on the relative phases of modes in the multimode fiber, so they are extremely sensitive to external perturbations of the fiber. These perturbations can locally appear in the fiber without disrupting the entire optical assembly. If the refractive index of the outside medium of the fiber is changed, it can cause variations in the speckle pattern at the fiber output. Thus, by changing the refractive index of the outside medium the speckle pattern at the output fiber varies and its influence can be observed. In this paper we demonstrate the influence of the refractive index of liquids in the speckle pattern obtained by a multimode fiber. In order to obtain greater sensitivity of the experimental measurement, the fiber is bent in a U-shape and immersed in a liquid. The core and cladding are 240 microns and 250 microns, respectively. The intensity speckle field is then captured by a CCD camera in digital image format and processed by the computer with a Matlab program. The portion of fiber exposed to the disturbance of the liquid is located 2 meters before the exit of the fiber. The portion of the fiber in contact with the liquid is curved with a radius of 2 mm.

Paper Details

Date Published: 11 September 2012
PDF: 6 pages
Proc. SPIE 8413, Speckle 2012: V International Conference on Speckle Metrology, 84131Q (11 September 2012); doi: 10.1117/12.978219
Show Author Affiliations
Carlos Galindez, Univ. de Cantabria (Spain)
Mauro Lomer, Univ. de Cantabria (Spain)
Luis Rodriguez-Cobo, Univ. de Cantabria (Spain)
J. M. Lopez-Higuera, Univ. de Cantabria (Spain)


Published in SPIE Proceedings Vol. 8413:
Speckle 2012: V International Conference on Speckle Metrology
Ángel Fernandez Doval; Cristina Trillo, Editor(s)

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