| Electromagnetic wave absorption is of great value in the fields of national defense technology and medical imaging.Various wave absorbing devices are widely used in equipment such as invisible cloaks,radar monitoring,and plasma detection.Since professor Geim and Novoselov,who won the Nobel Prize in physics in 2004,prepared single-layer graphene,its unique optoelectronic properties have provided new ideas for meeting the demand for high absorptivity of wave absorbers.When incident light irradiates the graphene microstructure,it can excite the graphene surface plasmon polaritons(SPPs)at a specific wavelength,so that the energy is localized near the microstructure.In addition,as a typical natural hyperbolic material,hexagonal Boron Nitride(hBN)can excite hyperbolic phonon polaritons(HPPs)in the mid-infrared band.Therefore,the combination of patterned graphene and hBN can not only provide a new absorption mechanism for graphene absorbing devices,but also expand new dimensions for the regulation of graphene absorption properties.Based on the graphene SPPs effect,this paper explores the tuning of the patterned graphene microstructure on the absorption performance of circularly polarized light(CPL),studies the absorption mechanism of graphene and hBN co-built microstructure absorbing devices,and proposes several patterns.The main contents of the new design of the graphene absorber are as follows:1.An infrared absorber based on square graphene array was proposed to realize the regulation of CPL absorption performance.The use of edge graphene plasmons(EGP)formed on square graphene disks(SGDs)in the x and y directions can enhance the absorption of CPL.The impedance matching theory and metal reflectors are used to minimize the reflectivity to achieve perfect light absorption.Combining the Fabry-Pérot(F-P)cavity theory with the linear fitting method,the position of the narrow-band absorption peak can be estimated well.In addition,by integrating SGDs of various sizes in one cell,multi-channel absorption with good absorption performance for CPL can be achieved.2.A mid-infrared broadband absorber realized by complementary ladder-shaped graphene/hBN was proposed to studied the regulation of the absorption performance by the hyperbolic plasmon phonon polaritons(HPPPs)and surface plasmon phonon polaritons(SPPPs)effects.The absorber can achieve nearly perfect broadband absorption within a 2.61μm bandwidth,and the absorption rate ranges from 11.67 μm to 14.28 μm over 90%.The SPPs excited on the upper and lower double-layer graphene surfaces cause the incident electromagnetic wave to oscillate up and down in the hBN layer,and the electromagnetic wave is coupled with the hBN lattice vibration to excite HPPs.Therefore,HPPPs and SPPPs are generated in the type I band and outside the band,which is significantly enhanced the absorption inside and outside the Reststrahlen(RS)band.At the same time,the impedance theory and power dissipation density explanation are based on the absorption performance and mechanism of the TG/hBN/CTG absorber.3.A narrow-band optical absorbing device based on striped graphene/hBN is designed.The absorber simultaneously excites SPPs on the graphene surface and HPPs on hBN to form a mixed plasmon phonon resonance,which enhances the incident light absorption in the mid-infrared band.The absorbers formed narrow-band absorption peaks at 12.82 μm and16.15 μm wavelengths,respectively.The absorption peak at 12.82 μm was mainly due to the intrinsic absorption of hBN,and the absorption rate was low.SPPPs contributed to the enhanced absorption of 16.15 μm wavelength.Due to the unique adjustable Fermi level of graphene,the absorption peak at 16.15 μm can be blue-shifted or red-shifted by increasing or decreasing the Fermi level of the strip-shaped graphene,making the absorber electrically adjustable.The position of the absorption peak of the absorber is not sensitive to the growth thickness of the silicon dioxide layer,which effectively increases the tolerance in the preparation of the absorber. |
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