设计了一种Au/VO2周期性方形孔洞阵列结构的红外吸收器, 利用时域有限差分法研究了吸收器的结构参数对吸收光谱的影响, 优选出VO2和Au膜层厚度分别为140 nm和80 nm, 孔洞边长和阵列周期分别为1.1 μm和1.2 μm时, 吸收可调控特性最为明显, 在2.3 μm处其高低温的吸收率差值可达80.3%.理论模拟计算了光以不同偏振、入射角入射时的吸收, 结果表明, 正入射时吸收器是偏振无关的; 斜入射时吸收器具有广角吸收的特点, 与TM偏振相比TE偏振下吸收器具有更强的角度依赖性.低温时吸收器中的电磁场呈高度局域化分布, 表现为强的吸收; 而高温时吸收器中的电磁场分布在吸收器表面, 吸收被抑制.所设计的吸收器吸收效率高, 吸收强度可以调控, 可应用于新型可调控智能光电器件.

An infrared absorber based on Au/VO2 periodic square hole array is designed in this paper. The effects of structural parameters on the absorption spectrum were calculated by the finite difference time domain method. The theoretical simulation results show that the absorption tunability was the most obvious at Au film thickness of 80nm and VO2 film thickness of 140nm, and the square hole length and array period were 1.1μm and 1.2μm, respectively. The absorption difference between high and low temperature can reach to 80.3% at 2.3μm. Considering the different polarization and incident angles, it is evident that the absorber was polarization-independent at normal incidence and wide angle at oblique incidence. The angular dependence was much stronger in TE polarization compared with TM polarization. In addition, the absorber presented strong absorption because of the highly localized electromagnetic field distribution under low temperature, but the electromagnetic fields are located at the surface at high temperature, which lead to suppressed absorption. The absorber can be applied to new tunable intelligent photovoltaic device due to the advantages of high absorption efficiency, tunable absorption intensity, and easy implementation.