Manipulation Electromagnetic Waves Of Artificial Microstructure Metamaterial And Its Application

The metamaterial is a kind of artificial synthetic material,which regulates the macroscopic physical properties of matter through the microstructural design of metal or dielectric material.This concept,which has been predicted to have subversive applications since it was proposed,receiving sustained and widespread attention over the years as a cutting-edge subject.Optical metamaterials are rapidly becoming the core research direction of metamaterials because of their abundant physical mechanism and important application prospect of photoelectric technology.It has been proved that it can use the effects of surface plasmon polaritons coupling,surface phonon polaritons coupling,mode resonance and mode annihilation to realize the modulation of electromagnetic parameters and the complex electromagnetic field.Besides,numerous new mechanisms,new properties,and new functions are still being explored and discovered.Based on the development opportunities and application basis of optical metamaterials brought by the breakthrough of micro-nano preparation technology in recent years,the main research directions of this paper are the regulation of electromagnetic waves by metamaterials and its application in optical detection.This thesis focuses on the following four aspects: the perfect metamaterial absorber,the regulation of infrared thermal radiation,the electromagnetic deflection of broadband,and the Cherenkov radiation of surface phonon polaritons.The main content and innovation points are as follows:1.A sub-wavelength grating has been elaborately designed to enhance the absorption of the monolayer graphene at ? = 1.55 ?m based on the coupled leaky mode theory(CLMT).The characteristics of mode resonance and mode coupling in nano-dielectric waveguides are studied.By matching the intrinsic loss of the material and the radiation loss of the structural leakage mode,the perfect narrow-band absorption of the high-quality factor is achieved where the absorption rate up to 99.98% and the quality factor up to 1034.Taking advantage of the bias-tunable chemical potential of graphene,the proposed structure can function as an adjustable absorber.The high figure of merit up to1329 and sensitivity with the value of 66 are achieved.With the ultranarrow absorption band and tunable peak positions,the graphene perfect absorber holds great potential application in sensing and biology.2.We propose a cascaded all-dielectric multilayer structure to selectively manipulate the thermal radiation characteristics in long-wavelength infrared(LWIR).A rectangular-like absorption(emission)spectrum is obtained by means of clipping of the absorption spectrum and the algorithm optimization.The broadband emissivity in non-atmospheric windows(6.3-7.5 ?m)can reach0.95 and the average absorption rate is below 3% in atmospheric windows(8-14 ?m).The multilayer structure is insensitive to the polarization of the incident waves and maintains a good rectangular absorptivity curve even with a large oblique incidence angle at 45 degrees.The outstanding properties of the nanostructures promise various applications in infrared sensing and thermal imaging.3.A polarization-independent wideband electromagnetic abnormal deflection metasurface is proposed by theoretical analysis and simulation.According to the generalized Snell's law,a series of unit structures with small dispersion and large phase coverage are designed by reducing the dispersion of the reflected phase and introducing more degrees of freedom to the unit.By optimizing and combining the units,the uniform phase gradient in the 0.9-1.2GHz broadband is formed,and the polarization-independent broadband deflection effect is realized.The abnormal reflections of the array on different polarization of the incident light are studied and the other arrays with different deflecting angles are obtained.4.The Cherenkov radiation based on the surface phonon polariton is realized in the hexagon boron nitride taking advantage of the one-dimensional metasurface.An equivalent running polariton wave of polarized is constructed by using the geometric phase of the unit in the hexagonal boron nitride.The excitation and propagation control of surface phonon polaritons can be realized under plane wave incidence.The modulation of incident wavelength,h-BN thickness,and oblique incidence angles on the Cherenkov radiation angle is studied.The physical mechanism of the Cherenkov radiation angle variation is analyzed.Besides,an array is proposed to realize the surface abnormal deflection in broadband.Due to the peculiarity of strong light localization in h-BN,the regulation of incident light can be completed in the deep subwavelength.