Abstract:
A polarization-insensitive, ultra-high-sensitive, simple microstructured photonic crystal fiber(PCF) basedsurface plasmon resonance (SPR) sensor for refractive index (RI), temperature, and magnetic field detection in the visible to the near-infrared region (540 to 1730 nm) is presented and analyzed by the finite element method (FEM). In this work, one of the simplest, symmetrical, and balanced structuresis designed by using only eight air holes in two rings, which makes it not only polarization insensitive but also the fabrication process easy and realizable. A combination of bimetallic plasmonic material such as gold with tantalum pentoxide (Au-Ta2O5) layers has been used to initiate higher SPR excitation to enhance the fiber sensing performance. The implementation of a Ta2O5 layer effectively addresses the issue of adhesion and concurrently mitigates costs by minimizing the reliance on gold as a plasmonic material. To ensure the feasibility of the operation, the sensor is designed so that the target analytes and plasmonic materials are strategically positioned on the periphery. Moreover, the sensor's sensitivity is not significantly affected by variations in the dimensions of the intended air holes, resulting in a sensor that exhibits a high degree of structural tolerance.
By optimizing its structural parameters, the sensor has attained a maximum wavelength sensitivity (WS) of 65000 nm/RIU, amplitude sensitivity (AS) of 2005.29 RIU−1, and a figure of merit (FOM) of 1625 RIU−1, wavelength resolution (WR) of 1.53 × 10−6 RIU, amplitude resolution (AR) of 4.99× 10−6 RIUfor x and y-polarization to detect an unknown analyte RI of 1.28−1.42.Furthermore, the sensor is applicable to detect a wide range of temperatures, 0 to 170°C for polydimethylsiloxane (PDMS), –110 to 70°C for ethanol, and magnetic field variations from 0 to 700 Oe with the corresponding maximum sensitivity of 34000 pm/°C for PDMS, 2500 pm/°C for ethanol, and 500pm/Oe for magnetic field. Moreover, the sensor is used to detect sucrose concentrations of 0 to 50% with a maximum WS of 66000 nm/RIU and WR of 1.51× 10−6; six types of cancer cells, among them the WS of 11000 nm/RIU for breast (MCF-7) and the AS of 5281.01 RIU−1 for cervical (HeLa); and different phases of malaria, including the WS of 18000 nm/RIU for schizont phase with WR of 5.55 × 10−6 RIU and the AS of 2042.77 RIU−1 for trophozoite phase.For all these detections, the sensor surpasses recently reported values. The sensor exhibits a mean fabrication tolerance of 39.23% of air holes.Its exceptional performance and favorable manufacturing likelihood make it a valuable candidate for biological, biomedical, and biochemical applications.
