High performance D-type plastic fiber SPR sensor based on a hyperbolic metamaterial composed of Ag/MgF2

Abstract

Hyperbolic metamaterials (HMMs) have attracted significant attention with regards to applications related to surface plasmon resonance (SPR) because of their heterodyne response induced by the multimode response and the high K-transfer mode (including transmission and dielectric ones) originated from their unique dispersive properties. However, most HMM-based applications related to fiber optic SPR are still at the theoretical simulation stages. This work reports the synthesis of HMMs using Ag and MgF₂. The resulting HMMs were used to fabricate an SPR sensor based on D-type plastic optic fibers (D-POFs). The sensor oscillation modes were theoretically analyzed using the effective medium theory and COMSOL. The optimal synthesis conditions were when the metal filling fraction (ρ) and the number of bilayers (N_bi) were equal to 0.5 and 3, respectively. Experiments showed that at the ambient refractive index in the 1.34–1.356 RIU range, the HMMs/D-POF sensor possessed high sensitivity (1875 nm per RIU), excellent linear response (with the correlation coefficient R² = 0.987), and reproducibility. Our sensor could also detect saccharin and 2, 6-di-tert-butyl-4-methyl phenol antioxidant 264 (BHT), both of which are toxic. Thus, both theoretical and experimental results showed the applicability of this sensor for real-life detection.