Li Shaoxian, Nugraha Priyo S, Su Xiaoqiang, Chen Xieyu, Yang Quanlong, Unferdorben Márta, Kovács Ferenc, Kunsági-Máté Sándor, Liu Meng, Zhang Xueqian, Ouyang Chunmei, Li Yanfeng, Fülöp József A, Han Jiaguang, Zhang Weili
Opt Express. 2019 Feb 4;27(3):2317-2326. doi: 10.1364/OE.27.002317.
Taking advantage of the tunable conductivity of graphene under high terahertz (THz) electric field, a graphene-metal hybrid metamaterial consisting of an array of three adjoined orthogonally oriented split-ring resonators (SRRs) is proposed and experimentally demonstrated to show a maximum modulation depth of 23% in transmission when the THz peak field reaches 305 kV/cm. The transmission of the sample is dominated by the antisymmetric and symmetric resonant modes originating from the strong magneto-inductive and conductive coupling among the three SRRs, respectively. Numerical simulations and model calculations based on a coupled oscillator theory were performed to explain the modulation process. It is found that the graphene coating impairs the resonances by increasing the damping of the modes and decreasing the coupling between the SRRs whereas the strong THz field restores the resonances by decreasing the conductivity of graphene.
利用石墨烯在高太赫兹（THz）电场下可调的导电性，提出并通过实验证明了一种由三个相邻且正交取向的开口环谐振器（SRR）阵列组成的石墨烯-金属混合超材料。当太赫兹峰值电场达到305 kV/cm时，该超材料在传输中显示出最大调制深度为23%。样品的传输分别由三个SRR之间强磁电感耦合和导电耦合产生的反对称和对称谐振模式主导。基于耦合振荡器理论进行了数值模拟和模型计算以解释调制过程。研究发现，石墨烯涂层通过增加模式的阻尼和降低SRR之间的耦合来削弱谐振，而强太赫兹场通过降低石墨烯的导电性来恢复谐振。
