Engineering metallo dielectric structures on optical fiber tips by self-assembling techniques

We investigate novel fabrication routes to realize regular and well-ordered micro and nanostructures on optical fiber tips by exploiting self-assembling techniques. Firstly, the breath figure (BF) methodology has been adapted to work directly on the optical fibers, enabling the formation of metallo-dielectric crystals on optical fiber tips. The pursued approach essentially consists in the preliminary preparation of a patterned polymeric film by the BF technique and in the successive metal deposition by evaporation. Accurate morphological characterization was carried out to qualify the fabrication process. The experimental results demonstrate the successful creation of a metallo-dielectric honeycomb pattern on optical fiber tips. The experimental spectral features are in good agreement with the numerical analysis, elucidating the photonic and plasmonic interactions occurring in the fiber tip device. The sensing properties of the optical fiber probes have been also successfully explored in terms of sensitivity to the surrounding refractive index changes demonstrating their potentialities for chemical and biological sensing applications. Finally, we report the preliminary results on the ongoing activities aimed to develop novel fabrication approaches of optical fiber sensing probes based on the assembly of microspheres into 2D colloidal crystals.