Study On Infrared Spectrum Regulation Based On Surface Plasmon And Optical Tamm State

Infrared light has a wide range of applications in communication,imaging,detection,sensing,military and so on.The purposeful and selective regulation of infrared spectrum by artificially designing subwavelength structures is of great significance.In this dissertation,the subwavelength structure is designed by using the surface plasmon and optical Tamm state effects and the coupling principle between modes to achieve effective regulation of near-infrared and mid-infrared spectra.The main work is as follows:1.In the near-infrared band,a gold(Au)-dielectric-gold(Au)multilayer film rectangular hole array was designed based on the effect of metal surface plasmon.The transmission properties of the structure were studied by the finite difference time domain(FDTD)method,and the generation mechanism of the transmission peak was analyzed.The results show that there are multiple transmission peaks in the transmission spectrum of the structure in the near-infrared band.The position,intensity,and linewidth of the transmission peaks depend on the refractive index and thickness of the dielectric layer,the period of the lattice array,and the aspect ratio of the rectangular hole.By changing the structural parameters and the refractive index of the dielectric layer,the regulation of the transmission spectrum in the near-infrared band can be realized.2.In the mid-infrared band,a graphene nanoribbon structure was designed based on the surface plasmon effect of graphene.The spectral properties and electromagnetic field distribution of the structure were studied by using FDTD method.The results show that the tuning of the resonance peak can be achieved by changing the number of graphene nanoribbons in one period,the width of the nanoribbons,the distance between the ribbons,and the bias voltage applied to graphene.The Fabry-Perot(F-P)model was used to explain the reason for the formation of resonace peaks.On this basis,a graphene-based mid-infrared multi-channel tunable narrow-band absorber was designed.3.In the mid-infrared band,a silicon carbide(Si C)-photonic crystal heterojunction-silicon carbide(Si C)structure was designed based on the properties of optical Tamm state and polar dielectrics supported phonon polariton.The FDTD method was used to simulate the transmission/absorption spectra and electric field distribution of the structure.Meanwhile,the transmission/absorption spectra were theoretically calculated using the coupled harmonic oscillator model.By adjusting the structural parameters,the polarization state of the incident light,and the incident angle,the generation and coupling of the modes can be controlled,and the adjustment from one absorption peak to four absorption peaks can be realized.4.Based on the coupling between graphene surface plasmon polariton and Tamm phonon polariton,a composite structure was designed.The absorption characteristics of the structure were studied numerically and theoretically by using the finite difference time domain method and the coupled harmonic oscillator model.The results show that the mode coupling and absorption strength can be tuned by adjusting the thickness of the air layer and the Fermi level of the graphene ribbons.Selecting reasonable parameters can achieve strong coupling of the two modes,resulting in perfect absorption of two frequencies.The sensing performance of the dual-frequency absorption structure is analyzed,the sensitivities of the two branches are S=4570 nm/RIU and S=4690 nm/RIU,respectively,and the figures of merit are FOM=109 RIU^-1and FOM=99 RIU^-1,respectively.The sensing sensitivity of this structure is high,and it has great application potential in high-performance refractive index sensing.