A circular-polarization metastructure (MS) with switchable functions connected to the transition from electromagnetically induced transparency (EIT) to electromagnetically induced absorption (EIA) is theoretically proposed under the action of circularly polarized (CP) waves in the terahertz (THz) band. Additionally, we use the phase-change material vanadium dioxide (VO₂) to achieve functional transformation. The MS is mainly composed of two metal bright modes and a VO₂ resonator. When the VO₂ is insulating, the EIT with a high and wide transmission window is realized between 0.460 THz and 0.911 THz due to the coupling between two bright modes. Once VO₂ reaches the metal state, the original high transmission window is transformed into the high absorption window and the phenomena from EIT to EIA (vice versa) are successfully achieved from 0.460 THz to 0.911 THz. The group delays and group index of EIT are 161 ps and 1126, respectively. The simulation results of EIT and EIA are verified by fitting the theoretical two-oscillator model.

在太赫兹（THz）波段的圆极化（CP）波的作用下，理论上提出了一种具有可切换功能的圆极化元结构（MS），该结构与从电磁感应透明（EIT）到电磁感应吸收（EIA）的转变有关。此外，我们使用相变材料二氧化钒（VO ₂）来实现功能转变。MS主要由两个金属亮模和一个VO ₂谐振器组成。当VO ₂绝缘时，由于两种亮模式之间的耦合，在0.460 THz和0.911 THz之间实现了具有高且宽传输窗口的EIT。一次 VO ₂达到金属态，原来的高透射窗口转变为高吸收窗口，从 0.460 THz 到 0.911 THz 成功实现了从 EIT 到 EIA（反之亦然）的现象。EIT 的群延迟和群指数分别为 161 ps 和 1126。通过拟合理论双振荡器模型验证了 EIT 和 EIA 的仿真结果。