Design and performance analysis of a dual-core gold-coated PCF-based plasmonic RI sensor for the detection of bio-analytes

This paper presents a straightforward sensor design based on a surface plasmon resonance (SPR) mechanism, utilizing a gold-coated dual-core type photonic crystal fiber (DCPCF-SPR) for the detection of diverse bioorganic biochemical analytical molecules in the spectral ranges of visible to near infrared (0.5–2 μm) wavelength. With two major hexagonal ring lattices and many circular air holes, the sensor construction is made to be less complicated, and the external surface of the designed structure is coated by a layer of gold (Au) that is 40 nm depth as plasmonic material depending on chemical adoption and excellent sensing performance. employing the finite element method (FEM), the detecting functions were examined for the chemical analytes in the measurement of refractive index range from 1.33 to 1.42. The maximal wavelength sensitivity (WS) and amplitude sensitivity (AS) of the proposed sensor were 27,000 nm/RIU and 1701.69 RIU⁻¹ with the resolutions of 3.70 × 10⁻⁶ RIU and 5.88 × 10⁻⁶ RIU, respectively, and 482 RIU⁻¹ was found as a maximum figure of merit (FOM). Placing the plasmonic material and analyte sensing layer on the DCPCF's outside is noteworthy in the design, as it indicates the feasibility of easier manufacturing processes. Following to these outcomes and a simple structural design, the suggested distinctive sensor can be potentially applicable for refractive index (RI) detecting the biochemical solutions, biomolecular substances, and biological samples.