Double-layered side-polished ultra-highly sensitive photonic crystal fiber-based surface plasmonic refractive index sensor

In this work, we offer a double-layered side-polished ultra-highly sensitive photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor for various biochemical analyte detection. Gold with titanium oxide (TiO 2 ) as an adhesive layer has been employed acting as the plasmonic material. This study is fully based on simulation with finite element method for numerical inspection. Analyte channel along with a perfectly matched layer as the boundary condition has been placed at the outermost section of the sensor. After regulating different parameters, we attain a maximum wavelength and amplitude sensitivity of 138,800 nm/RIU and 2868 RIU −1 , respectively, with a sensing range of 1.33–1.425 refractive indices of the analytes. Minimum wavelength resolution of 7.20 × 10 –7 RIU is observed which ensures superior detection accuracy. In addition, the sensor achieves an ultra-high figure of merit (FOM) of 5783 RIU −1 which certifies an excellent detection limit. The FOM is the highest among all the previously reported PCF-SPR sensors to the best of the authors’ knowledge up to date. The sensor also reveals a very low average confinement loss of 2.40 dB/cm which assures practical feasibility by minimizing complexity associated with sensor length and splicing. A discontinuous plasmonic material layer has been used in the sensor which enhances cost-efficiency and sensitivity factor. On account of ultra-high sensitivity, low confinement loss, and excessive FOM, our proposed sensor can be very convenient and impressive in detecting various liquid biological and biochemical analytes.