Effect of the electric field induced birefringence on the slab waveguide evanescent‑wave sensor sensitivity
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Date
2022
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Publisher
Université de M'sila
Abstract
We have investigated the potential of using the E-field induced birefringence for improving
the sensitivity of uniaxial anisotropic slab waveguide sensor based on evanescent wave
interactions. LiNbO3
waveguide core was used as an example. We have calculated the
sensor sensitivity formulas for the two kinds of modes propagating simultaneously in the
waveguide sensor. In our study, we have distinguished between two different cases. The first
case when the electric field is applied along the optic axis (+c) of the LiNbO3
wave guiding
film (positive electric field); the second case when the electric field is applied opposite
to the optic axis (−c) of such uniaxial crystal (negative electric field). The obtained results
showed that, for positive electric field, increasing the electric field induces an increasing of
the total anisotropy which causes decreasing on sensor sensitivity. However, for negative
electric field, the increase of absolute values of negative electric field induces a decrease of
the total anisotropy, the latter increases the sensor sensitivity. On the other hand, the study
of the physical parameters on the sensor sensitivity showed that, to maximize the sensor
sensitivity, it is advisable to use isotropic substrate that has a refractive index as closer as
possible to the measurand index.
Description
Keywords
Evanescent wave · Induced birefringence · Planar waveguide sensor · Sensor sensitivity · Uniaxial anisotropy