Unraveling the role of plasmonics in gold nanoparticle-integrated tapered fiber platforms for sensing applications

We demonstrate the use of cost-effective tapered telecommunication fiber in refractive index-based sensing when operated in the visible range of wavelength. To fabricate the tapered fiber, a two-step chemical-etching method is adopted. The two-step etching method is quintessential in overcoming issues such as the uncontrollable etching of Ge-doped silica fibers by hydrofluoric acid. The work details the optimization of the etching process. The tapered fiber is then chemically treated to immobilize gold nanoparticles on it. Finally, the performance of the proposed Au-immobilized tapered fiber sensor probe is studied when excited with visible light. Different concentrations of sucrose are used to detect the refractive index sensitivity. Performance parameters such as sensitivity, full-width half maximum, the figure of merit, and quality factor are determined for the sensor probe.