Thin-core fiber structures with overlays for sensing applications.

ABSTRACT

We investigate thin-core fiber-optic structures with film overlays that can be used for sensing applications. The structures are formed by a section of thin-core fibers (SM630 or SM450) spliced between standard SMF-28 fibers. The fibers are coated with overlays using the layer-by-layer assembly technology based on sequential alternating adsorption of polymer monolayers via electrostatic attraction. Transmission spectrum of the structures exhibits resonance dips caused by interaction between cladding modes. We measure the shifts of spectra with increasing thickness of the overlay and with pH value of the external medium. We calculate the shift of resonance wavelengths, which we compare with the experiment.