MXene-Enhanced Plasmonic Sensor Utilizing Planar Waveguide Modes and Long-Range Surface Plasmon Polaritons for Ultrasensitive Detection
Rajeev Kumar, Sarika Pal, Narendra Pal, Alka Verma, J. P. Saini, Yogendra Kumar Prajapati
Abstract
In this article, a new hybrid structure of planar waveguide (PWG) and long-range surface plasmon resonance (LRSPR) sensor is analyzed analytically. The proposed sensor design comprised of 2S2G/Cytop/Silicon (Si)/Cytop/Silver(Ag)/MXene/sensing medium (SM). The proposed structure demonstrates normal mode splitting condition on strong coupling of PWG mode at Cytop-Si-Cytop interface and the LRSPR mode obtained at the Cytop-Ag-MXene-SM interface. The proposed PWG-LRSPR sensor accomplishes 42564 /RIU maximum imaging sensitivity when wave vector of both PWG and LRSPPs is matched. The imaging sensitivity and propagations length (PL) of the proposed PWG-LRSPR sensor is much higher than that of the conventional SPR and LRSPR sensor. The proposed sensor demonstrates a remarkable improvement in imaging sensitivity, outperforming sensor structures 1–5 and 7 by 97%, 22%, 96%, 56%, 47%, and 25%, respectively, while showing only a minor 1.7% reduction compared to sensor structure 6. Notably, it achieves the highest PL value of 1.0671 μm among all seven structures, maintaining exceptional sensitivity with minimal compromise. Transverse component of electric field (EF) variations at various layer interface of the proposed sensor design and other comparable seven sensor structures have also been analyzed. Hence, the proposed refractive index sensor can be suitably used for chemical and biochemical application whose RI lies in the vicinity of 1.33 to 1.34.