Numerical Study of Strong Coupling-Enabled Dual-Mode Single-Nanoparticle Virus Detection Based on Magneto-Plasmon in a Magneto-Optical Metamaterial

Magneto-plasmonic (MP) nanostructures have received significant attention, as they are highly advantageous for ultrasensitive and label-free biosensing applications. Currently, most reported MP biosensors focus on detecting changes in solution concentration or refractive index and operate exclusively in single-channel sensing modes, whereas the detection of viral particles has rarely been explored. In this numerical work, we have proposed a dual-mode magneto-plasmon method of detecting virus particles via modes strong coupling in a magneto-optical metamaterial using finite-difference time-domain simulations, composed of the Ag square hole disk array and a MO layer. Owing to the strong coupling, two Kerr reversals are observed in the spectrum of polar Kerr rotation. Such findings pave the way for developing dual-mode magneto-plasmon biosensors, with sensitivity S1 = 307.71 nm/RIU and S2 = 524.38 nm/RIU and high figure of merit (FoM) values of FoM1 = 3.41 × 104/RIU and FoM2 = 8.73 × 104/RIU, respectively. The FoM achieved is at least 1 order of magnitude higher than the previously reported results of the same kind (755/RIU and 1823/RIU). Furthermore, based on the high sensing performance, the dual-mode virus-detecting method is achieved, theoretically capable of counting the number of PP01 bacteriophage precisely in the cavity of the proposed MP metamaterial.