Lossy mode resonances dependence on the geometry of a tapered monomode optical fiber

The geometry of a tapered single-mode optical fiber influences the formation and sensitivity of lossy mode resonances generated by the deposition of a polymeric thin-film employing the layer-by-layer electrostatic self assembly technique. In this work, several waist diameters and waist lengths of a monomode optical fiber are analyzed both experimentally and theoretically to obtain some conclusions about their influence on the behavior of this kind of devices. The transmitted optical power is studied as a function of the wavelength to estimate the sensitivity of this system. According to the results obtained, this sensitivity increases as a function of the waist length, whereas it decreases as a function of the waist diameter. What is more, depending on the combination of waist length and waist diameter, important power changes up to 45 dB can be reached at specific wavelength ranges of the electromagnetic spectrum, which can be used for accurate detection of small changes in the nanocoating properties induced by a specific analyte. This behavior can lead to sensing applications based on the combination of lossy mode resonances and tapered monomode optical fibers. (C) 2012 Elsevier B.V. All rights reserved.