Polarization-insensitive complementary metamaterial structure based on graphene for independently tuning multiple transparency windows
Hailong Huang(黄海龙)1,2, Hui Xia(夏辉)2, and Hongjian Li(李宏建)2, †
1 The Research Department, Beijing Zhongkexin Electronics Equipment Co. Ltd, Beijing 101111, China 2 School of Physics and Electronics, Central South University, Changsha 410083, China
Polarization-insensitive multiple transparency windows are obtained with a graphene-based complementary metamaterial structure in terahertz regions, which is composed of two kinds of monolayer graphene perforated in shapes of a cross and four identical split rings that construct a resonator. The geometric parameters of resonators are different from each other. Numerical and theoretical results show that the quantum effect of Autler–Townes splitting is the key factor for appearance of transparency windows within the resonant dips. Further investigation demonstrates that by employing the fourfold-symmetry graphene complementary structure, polarization-independent transparency windows can be achieved. Moreover, multiple transparency windows can be separately manipulated over a broad frequency range via adjusting the chemical potential of the corresponding graphene resonators, and the bandwidth as well as resonance strength can also be tuned by changing the relative displacement between resonators each consisting of a cross and four split rings. The proposed metamaterial structure may be utilized in some practical applications with requirements of no polarization-varied loss and slowing the light speed.
Hailong Huang(黄海龙), Hui Xia(夏辉), and Hongjian Li(李宏建) Polarization-insensitive complementary metamaterial structure based on graphene for independently tuning multiple transparency windows 2020 Chin. Phys. B 29 114203
Fig. 1.
(a) The photograph of the unit cell of multi-band PIT MM structure with the detailed geometric parameters. (b)–(d) The preparation process for controlling chemical potential of graphene resonators via the adjustable method of two top electrostatic grating. (e) The picture of a practical device.
Fig. 2.
Simulated transmission spectra of three graphene resonators: (a) large-size structure and (b) small-size structure. (c) and (d) Simulated transmission curves of G1 and G2 under different relative distances d1 and d2, respectively. (e)–(j) Z-component of magnetic field (Hz) of each transmission dip with normally incident wave.
Fig. 3.
Simulated transmission spectra of the proposed MM structure with different relative displacements d1 (a)–(d) and d2 (e)–(h), respectively. (i)–(k) The Hz distributions of combined structure at the transmission dip for different d1 and d2.
Fig. 4.
Simulated transmission spectra of the proposed MM structure with different chemical potentials (a) Ef1 and (b) Ef2. The corresponding group delay with different chemical potentials (c) Ef1 and (d) Ef2.
Fig. 5.
(a) The transmission spectra of the proposed MM structure under different angles of the polarized wave. The Hz distributions of (b) α = 0° (TE mode) and (c) α = 90° (TM mode) at the first resonant dip.
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