提出一种石墨烯-金属超材料复合太赫兹传感器，充分利用石墨烯能带Dirac点附近费米能级对样品的灵敏响应结合超材料表面强局域电场实现了对谷氨酸溶液浓度的多维超灵敏传感。实验结果表明，传感器在频率f =0.58 THz处存在一个明显的透射峰，且该透射峰幅值随谷氨酸溶液浓度的增加先升高后降低。若以透射峰幅值作为传感指标，器件能够探测到的最低浓度在10⁻¹ fg/mL量级。另外，从传感器的透射波相位差-频率关系曲线中提取的斜率与浓度具有类线性关联，这意味着相位差信息也可以作为有效的传感指标。结合透射幅值和相位差两个传感指标，器件可以实现对谷氨酸溶液浓度的超灵敏精确检测。文中提出的器件为发展基于太赫兹超材料的超灵敏氨基酸传感器提供了帮助。

An active ultrafast formation and modulation of dual-band plasmon-induced transparency (PIT) effect is theoretically and experimentally studied in a novel metaphotonic device operating in the terahertz regime, for the first time, to the best of our knowledge. Specifically, we designed and fabricated a triatomic metamaterial hybridized with silicon islands following a newly proposed modulating mechanism. In this mechanism, a localized surface plasmon resonance is induced by the broken symmetry of a C2 structure, acting as the quasi-dark mode. Excited by exterior laser pumps, the photo-induced carriers in silicon promote the quasi-dark mode, which shields the near-field coupling between the dark mode and bright mode supported by the triatomic metamaterial, leading to the dynamical modulation of terahertz waves from individual-band into dual-band PIT effects, with a decay constant of 493 ps. Moreover, a remarkable slow light effect occurs in the modulating process, accompanied by the dual-transparent windows. The dynamical switching technique of the dual-band PIT effect introduced in this work highlights the potential usefulness of this metaphotonic device in optical information processing and communication, including multi-frequency filtering, tunable sensors, and optical storage.

Recently reported plasmon-induced transparency (PIT) in metamaterials endows the optical structures in classical systems with quantum optical effects. In particular, the nonreconfigurable nature in metamaterials makes multifunctional applications of PIT effects in terahertz communications and optical networks remain a great challenge. Here, we present an ultrafast process-selectable modulation of the PIT effect. By incorporating silicon islands into diatomic metamaterials, the PIT effect is modulated reversely, depending on the vertical and horizontal configurations, with giant modulation depths as high as 129% and 109%. Accompanied by the enormous switching of the transparent window, remarkable slow light effect occurs.

We experimentally demonstrate for the first time an active all-optical ultrafast modulation of electromagnetically induced transparency-like effect in a hybrid device of sapphire/Si/metamaterial. From numerical simulations, it can be deducted that the tuning process is attributed to the coupling between the dark mode existing in split-ring resonators and the bright mode existing in cut wire resonators. The transmission amplitude modulation is accompanied by the slow-light effect. In addition, the ultrafast formation process is measured to be as fast as 2 ps. This work should make an important contribution to novel chip-scale photonic devices and terahertz communications.