Open AccessInfluence of an Al_2O_3 surface coating on the response of polymeric waveguide sensors
Author(s) -
Leila Ahmadi,
Marianne Hiltunen,
Jussi Hiltunen,
Sanna Aikio,
Jyrki Saarinen,
Seppo Honkanen,
M. Roussey
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.025102
Subject(s) - materials science , coating , refractive index , adsorption , linearity , bilayer , interferometry , optics , waveguide , polymer , optoelectronics , layer (electronics) , response time , aqueous solution , nanotechnology , membrane , composite material , chemistry , electronic engineering , biochemistry , physics , computer graphics (images) , organic chemistry , computer science , engineering
The responses of a polymer ridge waveguide Young interferometer with and without a bilayer of Al 2 O 3 /TiO 2 , fabricated by atomic layer deposition, are studied and compared when applied as an aqueous chemical sensor. The phase shift of the guided mode, as a result of the change in refractive index of the cover medium, is monitored. The results indicate that the over-coating affects the linearity of the sensor response. The effect of concentration on the linearity of the sensor response is investigated by applying different concentrations of water-ethanol solution. Although the performance of the sensor is improved by the additional layers, the study reveals a non-monotonic behavior of the device. We show that it comes mainly from the adsorption of ethanol molecules on the surface of the films. Such an understanding of the platform is crucial for sensing of analytes involving polar molecules.
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