Optimal Design And Control Of Periodic Trapezoidal Metamaterial Absorber

Metamaterials are artificially made materials with extraordinary physical properties not found in natural materials.With these special physical properties,it is possible to artificially design their electromagnetic characteristics.In recent years,the research and application on metamaterial absorbers have developed rapidly.In this paper,two kinds of metamaterial absorbers are designed for the effective ways of reducing the excessive consumption of traditional energy,such as solar absorption and radiative cooling,and the Finite-Difference Time-Domain method is used for calculation and analysis the absorption characteristics.For solar absorption,a composite trapezoidal solar broadband absorber is designed in this paper.The absorber has high absorptance and wide absorption band in the wavelength range of 0.3-2.5?m,the key to the high absorptance are the Surface Plasmon Polariton and Magnetic Polaritons excited at the interface of the media and the metal.In this paper,the response of the absorptance spectrum to the change of the structural parameters of the absorber is discussed.The size of the absorber is adjustable within a certain range.Through the study of the variation of the absorptance at the peak energy density of solar radiation at?=0.5?m with the incident angle,it is proved that the absorber has good absorption performance when the incident angle is 80 degrees.Aiming at the goal of dynamic radiative cooling,a periodic trapezoidal VO₂-Ge multilayer film absorber is designed.Due to the phase transition characteristic of VO₂ at68^oC,the absorptance curve of the absorber is very different in the spectrum band of3-15?m when VO₂ is insulating state and metal state,the absorptance is high when the temperature is high,and low when the temperature is low,so as to realize the purpose of dynamic regulation of emissivity for radiative cooling.The absorption mechanism of the absorber is different when VO₂ is in different phase states.Studies show that when VO₂ is in insulating state,the absorption mechanism of the absorber is magnetic resonance and SPP resonance,and when VO₂ is in metal state,it is because of the generation of slowlight guide mode.In this paper,the spectral absorptance characteristics of the absorbers in the two phase states are investigated as a function of the number of layers and the incident angle of the electromagnetic waves.The results show that the absorber designed in this paper is insensitive to the incident angle.