| In recent years, the research of surface plasmon polariton (SPP) is just unfolding, and the metal coated cavity which is based on the SPP mode has gradually attracted the attention of researchers. SPP is a kind of surface electromagnetic waves, the electromagnetic field is confined to the interface of dielectric and metal nearby, this constraint leads to the enhancement of electromagnetic field at the interface, thus the characteristic makes SPP widely used in plasma waveguide, surface plasma sensor and surface enhanced Raman scattering fields.This paper mainly studies metal-coated cylindrical resonant cavity which is based on surface plasmon mode. Firstly, we introduce the basic characteristics of the plasma and the surface plasmon polariton, and briefly describe several excitations of surface plasmon polariton. Secondly, we derive the wave equation in cylindrical waveguide, the electric field angular component of cylindrical cavity and the eigenvalue equation of metal-coated cylindrical resonant cavity mode from Maxwell’s equations in theory. Then we solve the resonant wavelength and the wave vector of resonant cavity mode in the numerical method by mathematical software, and we derive field distribution, effective refractive index, quality factor (Q-factor), sensitivity and detection limit. Finally, we analyze the mode characteristics and the sensing properties of metal-coated cylindrical cavity in detail, and we change the cavity structure parameters and draw the dispersion curves, the electric field distribution, and the relation curves of Q value, sensitivity and detection limit. And we find the supermodes coupling phenomena of SPPs mode and each order TM modes in metal-coated cylindrical cavity for the first time, and analyze that the sensitivity enhancement effect of SPPs mode to each order TM modes is at least two orders of magnitude, which lays the theoretical foundation in biochemical sensing applications of metal-coated cylindrical cavity. |
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