Highly efficient second harmonic generation assisted by the quasi-bound states in the continuum from AlGaAs meta-gratings

Qiu, Yu; Yan, Dexian; Li, Xiangjun; Zhang, Le; Li, Jining

doi:10.1016/j.optcom.2023.129772

Cited by 3 publications

(1 citation statement)

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“…This coupling usually produces a quasi-BIC peak by breaking the symmetry between structures, i.e., by adjusting one of the structural parameters [20][21][22][23][24]. The BIC generated by such structures is called the BIC of symmetry protection [25][26][27][28][29]. Another kind, although it is composed of two symmetric structures, the nature of its generation of BIC for the two modes (electric dipole and magnetic dipole) between the mutual coupling, that is, in the process of changing the structural parameters, always maintains the symmetry of the hypersurface structure is not broken [30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Conversion and Active Control between BIC and Absorber in Terahertz Metasurface

Xi,

Chen

2024

Photonics

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A multifunctional switchable metamaterial device based on graphene, a gold layer, polyimide, vanadiµm dioxide (VO2), and the sapphire substrate is designed in this paper. The top layer consists of a gold wire, graphene, and two split-ring resonators with the same parameters. By adjusting the Fermi level of graphene, the regulation of BIC and quasi-BIC is realized, and the conversion between BIC and absorber is realized by adjusting the conductivity of VO2. When the device is converted into a wave-absorbing device with single-band absorption characteristics, the Fermi level of graphene at this time is 0.001 eV, the absorption peak at 0.820 THz is higher than 99.5%, and when the Fermi level of regulated graphene is 1 eV, the absorption peak at 0.667 THz is also higher than 99.5%. The peak frequency of the device is 0.640 THz when it converts to quasi-BIC. To the best of our knowledge, this is the first time that the conversion and regulation of BIC and absorber have been achieved using these two phase change materials. Moreover, by adjusting the parameters of the metamaterial structure, the working efficiency and frequency of BIC and absorber can be dynamically adjusted. The electric field distribution and surface current of metamaterials are further studied, and the physical mechanism of effective absorption and BIC is discussed. These results show that the metamaterials proposed in this paper have many advantages, such as terahertz absorption, BIC, and active device control, and are of great significance for developing terahertz multifunctional devices.

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