石墨烯具有零带隙结构、低损耗性、动态可调性，在太赫兹吸收器应用中具有较高的实用价值。时域有限差分（FDTD）方法结合辅助差分（ADE）方法已经应用于太赫兹频段石墨烯吸收器的仿真分析中，但该方法需要采用极小的网格剖分石墨烯区域，导致其对石墨烯吸收器计算效率低。因此，提高计算效率尤为重要。

本文在分析石墨烯相关理论和混合显隐式时域有限差分（HIE-FDTD）方法稳定性条件的基础上，采用ADE方法将太赫兹频段石墨烯的带内电导率引入到HIE-FDTD方法中，从而得到了石墨烯中色散HIE-FDTD方法的迭代公式，并对该方法的稳定性条件、CPML吸收边界、总场/散射场边界以及周期边界进行详细推导。在数值仿真中，通过无限大石墨烯结构验证色散HIE-FDTD方法的高效性。结果表明，该方法对石墨烯的仿真较FDTD方法计算速度更快。针对具有弯曲结构的石墨烯模型，在色散HIE-FDTD方法中引入共形技术形成了改进的色散HIE-FDTD方法，并采用改进的色散HIE-FDTD方法与色散HIE-FDTD方法分别对具有弯曲结构的石墨烯模型进行仿真。仿真结果表明，在保持相同计算精度条件下，改进的色散HIE-FDTD方法计算速度较色散HIE-FDTD提高了5倍。

最后设计了石墨烯的单频带和双频带太赫兹吸收器，并采用改进的色散HIE-FDTD方法对其进行了仿真分析。仿真结果表明，单频带石墨烯吸收器在2.68 THz附近对入射波的吸收率可达到99.8%。双频带石墨烯吸收器在1.66 THz和3.25 THz附近对入射波的吸收率均大于96%。因此，所设计的吸收器达到了对入射波较理想的吸收效果，该结构具有一定的参考价值。

Graphene has zero band gap structure, low loss and dynamic adjustability, which has high practical value in the application of terahertz absorbers.Finite difference time domain (FDTD) method combined with assisted difference (ADE) method has been applied to the simulation analysis of graphene absorber in terahertz band, but this method requires a very small mesh to divide the graphene region, which leads to its low calculation efficiency for the graphene absorber.Therefore, it is very important to improve the computing efficiency.

In this thesis, based on the analysis of graphene-related theories and the stability conditions of the Hybrid Explicit Implicit Finite Difference Time Domain (HIE-FDTD) method, uses the ADE method to introduce the in-band conductivity of the terahertz band graphene into the HIE-FDTD method. In this way, the iterative formula of the dispersion HIE-FDTD method in graphene is obtained, and the stability conditions of the method, the CPML absorption boundary, the total field/scattering field boundary and the periodic boundary are derived in detail. In the numerical simulation, the high efficiency of the dispersive HIE-FDTD method is verified through the infinite graphene structure. The results show that this method is faster than FDTD method in the simulation of graphene. For graphene with a curved structure, the conformal technology is introduced into the dispersive HIE-FDTD method to form an improved dispersive HIE-FDTD method, and the improved dispersive HIE-FDTD method and the dispersive HIE-FDTD method are used for the curved structure respectively. Graphene is simulated. The simulation results show that the calculation speed of the improved chromatic dispersion HIE-FDTD method is 5 times higher than that of the chromatic dispersion HIE-FDTD under the condition of maintaining the same calculation accuracy.

Finally, the graphene single-band and dual-band terahertz absorbers are designed, and the improved dispersion HIE-FDTD method is used to simulate and analyze them. The simulation results show that the single-band graphene absorber has an absorption rate of 99.8% for incident waves near 2.68 THz. The absorption rate of the double-band graphene absorber to the incident wave is greater than 96% near 1.66 THz and 3.25 THz. The above results show that the designed absorber achieves an ideal absorption effect on the incident wave, and this structure has a certain reference value.

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