Développement de capteurs à fibre optique basés sur la résonance ...

Résumé Article 2 (en anglais)
Preface to article 2
The Effects of Polarization of the Incident Light
Modeling and Analysis of a SPR Multimode Optical Fiber Sensor
It is well know that the SPR can only be excited by p-polarized light. In the other hand, the
phenomenon of the mode mixture as the light rays propagate through a multimode optical fiber has
been recognized for a long time. Then which effect is more important in the SPR multimode fiberoptic
sensor Since our sensor is aimed to detect the slight variations of a monitored parameter and
moreover to interpret the small signals, a theoretical model as precise as possible is expected. The
influences of the polarization of incident light with respect to the input end face of the fiber to a
multimode SFR fiber-optic sensor will be answered in this paper.
We start with the earlier conclusion[ 11 declared that the light energy transmitted out of the fiberoptic
sensor is not affected by the polarization direction of the incident light, and show the
experimental results who indicate the apparent differences of the normalized light power transmitted
out of the fiber between the illuminations of p- and s- polarized light. Then an accurate 3D model
based on geometric optics is developed where the spatial variations of the electric field vector during
the propngation of the skew rays in the multimode liber are investigated, The computations are in
goad inccinents with the experiments. Further studies have drawn out the conclusions as below:
The polarization of the incident light has much influence while the SPR
transducer is located near to the input end of the fiber.
The polarization of the light source has not much influence while the SPR
transducer is far from the input end of the fiber. Therefore, a consistent
explanation to the previous conclusion[1] is reached.
Nevertheless, the accurate model is proposed to use if the small sensing
signals need to be quantitatively interpreted.
This research not only clarifies the fundamental concepts but also makes possible to characterize
the metal film, the self-assembled alkyithiol monolayer and the antibody and antigen layers
demonstrated in the following articles.
References
1. C,Ronot-Trïohi, A.Trouillet, C.Veillas, A.El-Shaikh and I I.Gagnaire. Fibre optic chemical sensor based on
surface plasmoti monochromatic excitation, Analytica Chimica Acta, 319(1 996) 121-127
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