Hollow-core Anti-resonant Fiber Plasmonic Sensor: Physics, Design, and Simulations

Next-generation sensing technologies require high-performance sensors that offer ultra-low loss with enhanced sensitivity. To achieve this, we propose a hollow-core anti-resonant fiber (HC-ARF) refractive index (RI) sensor utilizing the surface plasmon resonance (SPR) detection mechanism for superior optical sensing performance. The proposed sensor model features a single ring of uniformly arranged regular cladding tubes, each coated with a thin plasmonic metal layer to facilitate strong coupling between the core and plasmon modes. Through rigorous finite element modeling (FEM) simulations, the fiber structure is carefully optimized and sensing performance is investigated to obtain ultra-low loss and high detection sensitivity via wavelength interrogation. The simulation results show that the proposed HC-ARF sensor achieves losses up to two orders of magnitude lower than conventional solid-core fiber sensors. Notably, the sensor achieves enhanced wavelength sensitivity (WS) of 6500 and 11,500 nm/RIU for analyte RIs of 1.33 and 1.43, respectively, effectively spanning the visible to near-infrared spectrum with a broad sensing range from 1.25 to 1.44. Moreover, it shows stable performance under tight bending conditions with 80 cm bend radius and ±4% variations in geometric parameters. Thanks to its low-loss, wide detection range, and exceptional performance, enabling such sensor in real-time RI monitoring applications, such as glucose and sucrose concentration analysis, cancer cell detection, and SARS-CoV-2 identification.