偏振选择可调谐双带太赫兹吸收器

Polarization-Selective Tunable Dual-Band Terahertz Absorber

摘要:

提出并研究了一种偏振选择可调谐双带太赫兹吸收器。吸收器由顶层方形劈裂石墨烯环、中间SiO₂介质层以及底层金反射层组成。基于时域有限差分法的仿真结果显示,该吸收器在不同偏振光入射下均可以实现双带高效率吸收。x偏振光时在7.86和12.63THz处的吸收率分别为97.9%和91.2%；y偏振光时在6.30和10.52THz处的吸收率分别为94.1%和93.2%。通过改变石墨烯费米能级,可以对两个偏振的双带吸收峰波长进行调谐。此外,研究了介质层厚度和石墨烯劈裂环的物理参数对共振吸收峰的影响。因为在两个偏振状态下都能产生双带高吸收,所以此吸收器在太赫兹偏振成像、太赫兹传感、选择性光谱检测和偏振复用等领域有重要的潜在应用价值。

Abstract:

A polarization-selective dual-band tunable terahertz metamaterial absorber is proposed and investigated. The absorber is composed of square split graphene rings, a SiO₂ dielectric layer, and a Au reflection layer. The finite-difference time-domain simulation results show that the absorber can achieve dual-band high-efficiency absorption under different polarization light incidence. When the incident light is x-polarized, the absorption rates at 7.86 and 12.63THz are 97.9% and 91.2%, respectively; when the incident light is y-polarized, the absorption rates at 6.30 and 10.52THz are 94.1% and 93.2%, respectively. By changing the Fermi energy of graphene, the wavelengths of the dual-band absorption peaks of the two polarizations can be tuned. In addition, the effects of the thickness of the dielectric layer and the physical parameters of the graphene split ring on the resonant absorption peaks are investigated. Because dual-band high absorption can be generated in both polarization states, this absorber has important potential applications in terahertz polarization imaging, terahertz sensing, selective spectral detection, and polarization multiplexing.