三维拓扑绝缘体超材料光电效应仿真

Simulation of the Photoelectric Effect in Three-dimensional Topological Insulator Metamaterial

摘要:

提出了一种基于三维拓扑绝缘体Bi1.5Sb0.5Te1.8Se1.2的周期性方环阵列超材料结构。仿真结果表明超材料结构的表面等离子体共振强度随阵列周期和方环内环尺寸的减小而增大,其中,当周期为300 nm或尺寸为25 nm时,可以限制80%的电磁波在表面态上。此外,通过仿真正、斜圆偏振光入射下超材料和非超材料结构的表面电场随偏振态的变化关系,得到了两种结构正、斜入射下的圆二色性；结果表明,超材料结构圆二色性数值为0.92,远大于非超材料结构,并且该超材料结构的圆偏振分量在总偏振光电流分量的占比有显著提升,这是因为有更多的自旋电子被圆偏振光从拓扑表面态激发到体导带上。

Abstract:

This paper proposes a metamaterial structure based on a periodic square-ring array of three-dimensional topological insulators (Bi1.5Sb0.5Te1.8Se1.2). Simulation results showed that the surface plasmon resonance intensity of the metamaterial structure was enhanced with decreases in the array period and size of the square ring, where 80% of the electromagnetic wave could be confined to the surface states when the period was 300nm or the size was 25nm. In addition, the circular dichroism of the metamaterial and non-metamaterial structures under the incidence of positive and oblique circularly polarized light were obtained by simulating the relationship between the variation of the surface electric field and polarization of the metamaterial and non-metamaterial structures under positive and oblique incidence. The circular dichroism of the metamaterial structure (0.92) was much larger than that of the non-metamaterial structure, and there was a significant increase in the ratio of the circularly polarized component to the total polarized component for this metamaterial structure, which was attributed to the fact that more spintronic electrons were excited by the circularly polarized light from the topological surface state to the body conduction band.