根据多尺寸结构特性和阻抗匹配理论,设计一种矩形层叠结构的超宽带完美吸收器。该吸收器由两层不同尺寸的金属-半导体薄膜-半导体组成,其可以激发多种谐振模式,实现超宽带的完美吸收。采用时域有限差分法研究和分析吸收器的吸收光谱和电磁场能量分布,以及偏振角和入射角对吸收性能的影响。数值计算结果表明,该吸收器在可见光-中红外范围内的平均吸收率高于97%,并具有偏振独立性;当入射角度为60°时,平均吸收率仍高于90%;宽波段的完美吸收由间隙表面等离激元、传导表面等离激元和法布里-珀罗谐振等多种模式的共同作用来实现。

According to the characteristics of the multi-size structure and the impedance matching theory, a perfect ultra-broadband absorber with a rectangular laminated structure is designed. The absorber is composed of two layers of metal-semiconductor films-semiconductors of different sizes, which can excite multiple resonance modes and achieve perfect absorption of ultra-broadband. The finite difference time domain method is used to study and analyze the absorption spectrum and electromagnetic field energy distribution of the absorber, as well as the influence of polarization angle and incident angle on absorption performance. Numerical results show that the average absorptivity of the absorber is higher than 97% in the range of visible light to middle infrared, and it is independent of arbitrary polarization. When the incidence angle is 60°, the average absorption rate is still higher than 90%. The wide band perfect absorption is achieved by the joint action of gap-surface plasmon polaritons, propagation surface plasmon polaritons and Fabry-Perot resonance.