Study On The Absorption Characteristics Of Infrared Metamaterial Based On Surface Plasmon

Metamaterial is a preparation of artificial electromagnetic material,with surface micro-nano structure.When the electromagnetic field enters in and interacts with the metamaterial,it tends to show some abnormal phenomena,such as abnormal refraction,backward wave,etc.Metamaterial has some electromagnetic properties which natural material do not have.These properties lead to the abnormal optical phenomena.It breaks the limitations of the traditional electromagnetic material and greatly improves the comprehensive performance of magnetic materials.Nowadays,metamaterial is a frontier interdisciplineof physics and material science.Comparing with traditional traditional absorbing device,metamaterial perfect absorbing device has many advantages,such as perfect absorption,spectral selectivity(adjustable working wavelength),etc.Considering these properties,metamaterial perfect absorbing device can be widely used in sensor,detector,stealth materials,etc.In recent years,the metamaterial perfect absorbing device has become one of the most popular topics in the field of nanometre optical.In the theory and method part,this dissertation firstly introduces the infrared absorption mechanism of the metamaterial perfect absorbing device,mainly including perfect absorption based on impedance matching theory and partial coherence theory of surface plasmon.Secondly,the paper expounds the model and method,which are used in the design and optimization of the infrared metamaterial perfect absorbing device,including the equivalent medium model method and equivalent circuit model method.Then,the next part is about core algorithm--finite difference time domain method used in simulation calculation in detail.In this dissertation,the specific researches are as follows:(1)Theoretically designing and simulating a rectangular structure of micro-nano short-wave infrared dual band gold metamaterial perfect absorbing device.The absorbing unit is with three layers structure,from the bottom,respectively is a continuous metal spacer of gold material layer,a continuum dielectric interval Si O2 layer,and a rectangular gold resonance structure.When the electromagnetic wave is normal incidence,the perfect absorption of the designed metamaterial device is achieved.The wavelength is 1.194 ?m and 1.596 ?m,and the respective absorption rate are 99.76% and 99.85%.Then the paper analyses the causes of perfect absorption mechanism.By analyzing the electric field distribution and current distribution,it shows that having a magnetic resonance between magnetic flux in the unit and the magnetic field component of the incident electromagnetic wave leads to perfect absorption of the designed metamaterial device.Meanwhile,in the process of realizing perfect absorption,local surface plasmon resonance(LSPR)and the local field are also enhancing.By analyzing the relatives among absorption rate of metamaterial perfect absorbing device,polarization direction of incident electromagnetic wave,and the stability of angle of incidence,it concludes that when the incident angle ofincident electromagnetic wave is in 60 degree range,no matter the incident electromagnetic wave of TE-polarization or TM-polarization,metamaterial perfect absorbing device has no major effects on incident electromagnetic wave absorption wavelength and the absorption rate.(2)Theoretically designing and simulating a long wave infrared dual band metamaterial perfect absorbing device with two groups of resonance structure layer and the dielectric spacer layer.The absorbing device unit has a multi-layer structure,from the bottom,respectively is a continuous metal spacer layer of gold material,a disc-shaped Si O2 dielectric spacer layer,a disc-shaped resonant structure gold layer,a disc-shaped Al2O3 medium interval layer and a disc-shaped gold resonance structure layer.When the electromagnetic wave is incident,metamaterial perfect absorbing device achieves perfect absorption,under the condition of the wavelength is 7.301 ?m and 11.042 ?m.The absorption rate respectively are 99.76% and 99.85%.The incident angle of the incident electromagnetic wave of TM-polarization increases to 60 degree,the absorption rate of the metamaterial perfect absorbing device remains to 94%.The incident angle of the incident electromagnetic wave of TE-polarization increases to 60 degree,the absorption rate of the metamaterial decrease to 86%.The reason of the absorption rate significant decline of the incident electromagnetic wave of TE-polarization is magnetic resonance.When the incident angle of the incident electromagnetic wave of TE-polarization increases,magnetic-field component in the horizontal magnetic field correspondingly significantly reduces.Consequently,it effects the magnetic resonance.(3)Based on the former two parts,this dissertation proposes a plan about the adjustable absorption curve of metamaterial perfect absorbing device.Through analyzing the temperature controlled phase change characteristics of vanadium dioxide material,this proposal is modified.By replacing gold material resonance structure mentioned in former two parts to vanadium dioxide material,the reversible conversion between single band absorption and dual band absorption of metamaterial perfect absorbing device can be realized by changing environment temperature.