Response of the transmission spectrum of tapered optical fibres to the deposition of a nanostructured coating

Fibre-Optic Chemical Sensor Approaches Based on Nanoassembled Thin Films: A Challenge to Future Sensor Technology

“…The optical properties of the tapered fibre waveguide are influenced by the profile of the conical tapering sections, by the diameter of the taper waist and by the optical thickness of the surrounding medium. The proportion of the power in the evanescent field, and thus the interaction with the surrounding medium, increases with decreasing diameter of the taper waist [23,24]. In the tapering section, the guided mode of the single mode fibre is converted into a mode of the waist, Figure 2.…”

“…In adiabatic tapers this is achieved without coupling to higher order modes. In non-adiabatic tapers the taper profile is such that a proportion of the light is coupled into higher order modes of the tapered section, which interfere to produce the channeled spectra reported for tapers of diameter of order 5 μm [23,25].…”

“…The detailed description of the fibre tapering procedure can be found elsewhere [23]. Briefly, a single mode silica optical fibre was tapered using the heat and pull technique.…”