Dual-blade-like shaped nanostructured metasurface inducing dual-band extinction for dye fluorescence enhancement

The author experimentally reports here strong fluorescence enhancement (FLE) induced by a gold nanostructured surface. The metasurface consisting of periodic arrays of dual-blade-like shaped nanostructures was fabricated on a glass substrate and manipulated to excite surface plasmons. The measured extinction spectrum has a dual band maximized at approximately 645 nm and 795 nm under a linearly polarized light illumination. The author employed the dye molecule IR125 as a fluorophore whose fluorescence was significantly boosted by near-field interactions between the plasmon and the molecule. The resulting FLE induced by the near-field enhancement is attributed to the plasmonic resonances and correlated to the extinction of the metal nanostructure. The calculated Purcell enhancement factor, which simulates a spontaneous emission enhancement of an emitting dipole placed in the vicinity of the nanostructure, is in good agreement with the measured FLE.