Localized surface plasmon sensor using a hetero-core structured fiber optic with gold island films

This paper reports the effect of applying a gold islands film to the hetero-core structured optical fiber, which is fabricated by annealing thin Au films of 3 nm and 5 nm thicknesses and its sensing performance for the RI changes. We experimentally observe that novel LSPR spectra for 1.333 RIU appear in the visible-to-near-infrared region depending on the shape of Au islands. The absorbance and spectral sensitivities for a given refractive index region of the tested solvents were obtained to be 4.81 AU/RIU and 517 nm/RIU, respectively, in the range of 1.333–1.384 RIU in the case of 5-nm-thick Au film annealed at 900°C.