Highly birefringent gold-coated SPR sensor with extremely enhanced amplitude and wavelength sensitivity

Abstract

In this manuscript, we present a unique and simply designed surface plasmon resonance-based PCF biosensor that shows high sensing performance. The numerical technique finite element method is utilized to evaluate the fiber's guiding characteristics. Our design has a thin layer of gold (Au) surrounding the fiber, which is a stable plasmonic material. The strategic arrangement of the circular-shaped airholes inside the fiber enhances the overall performance of the sensor. After precise investigation of the various fiber parameters, the maximum amplitude sensitivity was found to be 3.35 × 103 RIU−1 for x-polarization and 5.00 × 103 RIU−1 for y-polarization in a sensing range of refractive index 1.33–1.41. The sensor exhibited a maximum birefringence of 2.23 × 10–3 and a maximum wavelength sensitivity of 3.00 × 104 nm/RIU and 3.25 × 104 nm/RIU for x- and y-polarization, respectively. The sensor resolution (amplitude) is found to be 2.98 × 10–6 for x-polarization and 2.00 × 10–6 for y-polarization, whereas the sensor resolution (wavelength) is 3.33 × 10–6 and 3.08 × 10–6 for x-polarization and y-polarization, respectively. Moreover, we obtained a high figure of merit of 4.48 × 102 RIU−1 for x-polarization and 4.44 × 102 RIU−1 for y-polarization. For its simplicity in design and high performance, this biosensor has a wide range of applications in the field of sensing unknown biomolecules and organic substances.