Performance Enhancement of Gold Coated D-shaped PCF Sensor Using Monolayer MoS₂

In this paper, we theoretically propose a surface plasmon resonance (SPR)-based D-shaped photonic crystal fiber (PCF) sensor with gold coating and an overlayer of molybdenum disulfide (MoS₂) 2D material. We design a PCF sensor with the square lattice arrangement of air holes for sensing the analytes of refractive index ranging from 1.33 to 1.42, which includes most of the bio-samples. Further, we optimize the proposed sensor in terms of two different air hole radii, pitch distance, thickness of the gold layer, and 2D material. The detailed numerical results corroborate that the sensor exhibits a wavelength sensitivity of 20,200 nm/RIU without a coating of MoS₂ layer. However, it does exhibit an enhanced wavelength sensitivity of 22,800 nm/RIU with a high spectral resolution of 4.38 × 10⁻⁶ RIU when a monolayer of MoS₂ is coated onto the gold layer. In addition to wavelength sensitivity, we also compute the amplitude sensitivity which is 752 RIU⁻¹ with a resolution of 1.34 × 10⁻⁶ RIU. Besides, we carry out tolerance studies to ensure the robustness of the proposed sensor. Finally, polynomial fitting characteristics are investigated and the R² value is found to be 0.99825. The novelty of the proposed model relies upon the integration of an experimentally feasible D-shaped PCF structure with a 2D layer (MoS₂) coating. The sensing performance of PCF with MoS₂ coating has been barely studied in the past. We have done an extensive analysis of the performance of the PCF sensor with MoS₂ overlayer. As of the author’s knowledge, the proposed sensor shows higher sensitivity than the other MoS₂-coated refractive index PCF sensors reported so far. This study may turn out to be an impetus for further interest towards the PCF sensors via MoS₂ coating. Thus, the proposed D-shaped MoS₂-coated PCF sensor finds potential application in the detection of chemical and biological samples.