Design and Implementation of Fiber-embedded Plasmonic Structures in Microwires

The development of all-fiber plasmonic structures by thermally treating metal core/glass cladding microfibers enables direct light coupling from the distal end of fiber as well as their integration in optical fiber or planar integrated circuitry for hybrid architectures. All-fiber plasmonic tips with controlled geometrical characteristics can confine and enhance light nanofocussing with enhancement factors comparable to pure metallic tips while at the same time they offer mechanical robustness and compensation of the high losses induced by the metal due to the continuous re-excitation of the plasmon modes. Their fabrication though by tapering metal core/glass cladding microfibers is not trivial since due to the low viscosities of liquid metals, breakage of the metal core can occur leading to the formation of spheres. Microfluidics Finite Element Method - FEM simulations were performed for the determination of the appropriate heating conditions for the fabrication of high quality metal tips. Furthermore, by controlling the induced heat perturbation, metal spheres of uniform diameters can be formed for the development of in-fiber plasmonic resonators.