A surface plasmon resonance sensor based on photonic crystal fiber composed of magnesium fluoride and graphene layers to detect aqueous solutions.

In this paper, a new and simple structure of a photonic crystal fiber (PCF) surface plasmon resonance biosensor is designed for detecting aqueous solutions. The graphene and magnesium fluoride (MgF2) materials are used externally around the PCF to increase the sensitivity of the sensor. The performance of the sensor is analyzed using the finite element method. The numerical results show that the proposed PCF provides an average wavelength sensitivity (Sw) and amplitude sensitivity (SA) as high as 4000 nm/RIU−1 and 16,905.15 RIU−1, respectively, for analytes with refractive indices (RIs) ranging from 1.33 to 1.342. When the MgF2 layer is eliminated from the structure, the values of Sw and SA are decreased to 2500 nm/RIU−1 and 12,155.2 RIU−1, respectively. Therefore, it is concluded that adding an MgF2 layer externally on the graphene layer of the proposed PCF increases the Sw and SA parameters. It is also exhibited that by increasing the thickness of graphene layers, the confinement loss is enhanced, and the SA is decreased. In addition, by adding the thickness of the MgF2, both SA and confinement loss parameters are increased. The results also show a linear relationship between the parameters with a very high figure of merit (FOM) of 17,416.66RIU−1 and a resolution of 2.5 × 10–5. [ABSTRACT FROM AUTHOR]