Xia Zhang, Li Tinghui, Huang Yuqing, Yu Jing, Xinchun Li, Xia Yuhui, Yang Yuhan, Yinghua Wang, Qiang Wang
In this work, we demonstrate readily tunable EIT response, fluorescence enhancement, and heavy-metal ion detection within a single stacked ITO/Ag nanohole/poly(vinylpyrrolidone) (PVP) architecture. The observed EIT originates from the coupling between Fabry–Pérot (FP) resonances and Bloch surface plasmon polariton (SPP) modes. The fluorescence of dye molecules is significantly enhanced at the wavelength corresponding to the EIT transparency window, thereby enabling highly sensitive detection of mercury ions (Hg 2+ ). The coupling mechanism is elucidated by analyzing the mode field distributions in conjunction with coupled-mode theory. The EIT response can be widely tuned by varying the sphere diameter and etching duration in nanosphere lithography (NSL), a fabrication technique that is straightforward, cost-effective, and suitable for producing large-area, ordered nanostructures. These findings are expected to facilitate the practical implementation of EIT-based devices and sensing platforms.