The demand for multinarrowband absorber has attracted increasing interest among researchers in recent years. However, integrating multifrequency absorption, tunability, and high optical transparency into an absorber remains a crucial challenge. In this study, a multiband, tunable, and transparent microwave meta‐absorber is theoretically proposed and experimentally demonstrated. This meta‐absorber is composed of resonant patterns made from graphene and indium tin oxide (ITO), placed on a substrate of lithium niobate (LN). By introducing P‐type doping to reduce the resistance of monolayer graphene to around 300 Ω, the impedance matching of the absorber is promoted, consequently manifesting ten absorption points within 40 GHz. The electric field distribution analysis and an equivalent circuit model are employed to elucidate the physical mechanisms of the multiband absorber. Additionally, the lithium niobate dielectric layer possesses a substantial dielectric constant and exhibits phase transition characteristics with temperature changes. When the temperature increases to 250 °C, a comprehensive tuning range of more than 5.49 GHz within 40 GHz range is realized. The maximum tuning range for a single frequency point is 1.33 GHz. With the broadening of the band, the meta‐absorber can provide multiple tunable ranges, making it more favorable for practical applications in optical modulator and sensor.

中文翻译：

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具有多频谐振的可调谐透明石墨烯吸收器


近年来，对多窄带吸收器的需求引起了研究人员越来越感兴趣。然而，将多频吸收、可调性和高光学透明度集成到吸收器中仍然是一个关键挑战。在这项研究中，理论上提出了一种多波段、可调谐和透明的微波超吸收器，并进行了实验演示。这种 meta-absorber 由石墨烯和氧化铟锡 （ITO） 制成的谐振图案组成，放置在铌酸锂 （LN） 的衬底上。通过引入 P 型掺杂将单层石墨烯的电阻降低到 300 Ω 左右，促进了吸收体的阻抗匹配，从而在 40 GHz 内表现出 10 个吸收点。采用电场分布分析和等效电路模型来阐明多带吸收器的物理机制。此外，铌酸锂介电层具有相当大的介电常数，并表现出随温度变化的相变特性。当温度升高到 250 °C 时，在 40 GHz 范围内实现超过 5.49 GHz 的综合调谐范围。单个频率点的最大调谐范围为 1.33 GHz。随着波段的扩大，元吸收器可以提供多个可调谐范围，使其更有利于光调制器和传感器的实际应用。