Large Side Hole Polymer Optical Fiber-Based Surface Plasmon Resonance Sensor

A ZEONEX-based large side air hole polymer optical fiber (LSAHPOF) is proposed and numerically analyzed for surface plasmon resonance (SPR)-based sensing applications. The fiber has been successfully fabricated using a drawing tower facility and the fabrication process is designed such that the fiber core is fully exposed to the side air hole, enabling direct metal deposition onto the core surface. Gold has been considered as the plasmonic metal for the numerical analysis. The low optical loss of ZEONEX in the visible wavelength region, combined with the surface plasmon resonance (SPR) frequency of gold occurring in the same spectral range, makes ZEONEX an excellent material choice for SPR-based sensing applications. On the other hand, the humidity insensitivity of ZEONEX makes it well-suited for sensing applications in aqueous environments. The presence of a large side hole facilitates efficient metal coating and easy introduction/removal of the analyte, without adversely affecting the sensor's performance, even with increased hole size. The sensor’s performance has been numerically evaluated for RI of analytes as well as for detecting thickness of biolayer. The analysis reveals a maximum wavelength sensitivity of 3500 nm/RIU and a high resolution of 2.8 × 10⁻⁵ RIU and an amplitude sensitivity of 696 RIU⁻¹. On the other hand, the sensitivity for thickness of biolayer has been found to be 1.54 with a maximum resolution of 64 pm.