Two-dimensional Waveguide Metamaterials Sensing Characteristic Research

In the past few years, metamaterials have rapidly advanced from being a paradigm for engineering unique electromagnetic properties to forming a material base for functional devices. One of the most significant applications of metamaterial device is the sensor due to its breaking the limits of sensitivity and resolution of the traditional sensor. Therefore, metamaterial sensor may fuel the revolution of sensing technology.This thesis first introduces the properties of surface wave and the sensing principle of2D waveguide model, and investigates the influence of metamaterial layer on the waveguide model. This reveals the methods and laws that metamaterials can amplify evanescent wave, and enhance the sensitivity of the sensor.The main contents and conclusions obtained are as follows:In the first part, the property of surface wave under the2D waveguide model is introduced, and a layer of metamaterials is sandwiched between a semi-infinite cladding and the guiding layer, the dispersion equation of linear planar waveguide with a metamaterial layer and the sensitivity formula of the corresponding sensing model in TM mode are derived based on three layer linear planar waveguide, and investigates the influence of model parameters on the sensing performance. The simulation results show that the evanescent wave generated at the boundary between the guiding layer and the metamaterial layer excites a surface wave at the boundary between the metamaterial layer and the cladding, and the evanescent wave in the cladding can be amplified by the metamaterials without affecting the propagation constant of the waveguide. The sensitivity of the sensing model is significantly enhanced as compared with the traditional sensing model, and the sensitivity in TM mode is higher than that in TE mode.In the second part, the property of Kerr type nonlinearity is introduced firstly, and the metamaterial layer is sandwiched between a semi-infinite nonlinear cladding and the guiding layer, the dispersion equation of nonlinear planar waveguide with a metamaterial layer and the sensitivity formula of the corresponding sensing model in TE and TM modes are derived based on three layer nonlinear planer waveguide, and investigates the influence of model parameters on the sensing performance. The simulation results show that the evanescent wave generated at the boundary between the guiding layer and the metamaterial layer excites a surface wave at the boundary between the metamaterial layer and the nonlinear cladding, and the evanescent wave in the nonlinear cladding can be amplified by the metamaterials.The sensitivity of the sensing model is significantly enhanced as compared with the traditional sensing model, and the sensitivity in TM mode is higher than that in TE mode, the sensitivity in nonlinearity is higher than that in linearity, and the sensitivity in reverse symmetry mode is higher than that in symmetry mode.In the third part, the sensing mechanism of microresonator and surface plasmon resonator are introuduced at first, and a layer of mataterials is coated on the surface of the cylindrical dielectric waveguide. The dispersion relation of the cylindrical dielectric waveguide coated with a metamaterial layer is derived. The electric field distributions and resonant frequencies of the corresponding whispering gallery mode are computed and simulated, and its quality factors are obtained using finite element method. Numerical results of resonant frequency and electric field distribution are in good agreement with the analytical results. This confirms the validity of the numerical analysis. The simulation results show that the evanescent wave generated at the boundary between the guiding layer and the metamaterial layer excites a surface wave at the boundary between the metamaterial layer and the cladding (the analytes adsorbed or the surrouding medium around at the surface of the metamaterial layer), and the evanescent wave in the cladding can be amplified by the metamaterials. The sensitivity of the microdisk sensing model with a metamaterial layer is much higher than the one of the traditional microdisk resonator sensing model in both homogeneous sensing and surface sensing. The increasing thickness of the metamaterials leads to a further improvement of sensitivity. Moreover, the Q factor of the microdisk resonator coated with a metamaterial layer can be tailored by tuning the coupling distance between the straight waveguide and microdisk.