Citation:
Sergiy Korposh, Stephen W. James, Seung-Woo Lee, Stephen Topliss, Sammy C. Cheung, William J. Batty, and Ralph P. Tatam. Fiber optic long period grating sensors with a nanoassembled mesoporous film of
SiO2 nanoparticles. Optics Express, Vol. 18, Issue 12, June 2010, pp13227-13228
Abstract:
A novel approach to chemical application of long period grating (LPG) optical
fibers was demonstrated, which were modified with a film nanoassembled by the
alternate deposition of SiO2 nanoparticles (SiO2 NPs) and poly(diallyldimethyl
ammonium chloride) (PDDA). Nanopores of the sensor film could be used for
sensitive adsorption of chemical species in water, which induced the changes in
the refractive index (RI) of the light propagating in the cladding mode of the
optical fiber, with a concomitant effect on the transmission spectrum in the LPG
region. The prepared fiber sensor was highly sensitive to the change in the RI
of the surrounding medium and the response time was very fast within 10 s. In
addition, chemical infusion into the film was tested using a porphyrin compound,
tetrakis-(4-sulfophenyl)porphine (TSPP), which could be saturated within a few
min. The lowest detectable concentration of the TSPP analyte was 10 mu M. The
TSPP infusion led to the development of well-pronounced dual resonance bands,
indicating a large increase in the optical thickness of the film. The RI of the
film was dramatically increased from 1.200 to ca. 1.540.
