Abstract-Actively tunable terahertz electromagnetically induced transparency analogue based on vanadium-oxide-assisted metamaterials

• Zhaojian Zhang,  
• Junbo Yang, 
• Yunxin Han, 
• Xin He, 
• Jingjing Zhang, 
• Jie Huang, 
• Dingbo Chen, 
• Siyu Xu,  
• Wanlin Xie 
• • 
    

https://link.springer.com/article/10.1007/s00339-020-3374-2

We investigate the active control of electromagnetically induced transparency (EIT) analogue based on terahertz (THz) metamaterials integrated with vanadium oxide(VO2). Due to the insulator-to-metal transition of VO2, the amplitude of EIT peak can be actively modulated with significant modulation depth. Meanwhile the group delay within the transparent window can also be dynamically tuned, bringing the active control of slow light effect. Furthermore, we also introduce independently tunable transparent peaks based on double-peak EIT, and the group delay within each transparent window can also be independently controlled. Finally, based on broadband EIT, the active tuning toward quality factor of EIT is also realized. This work introduces active EIT control with multiple degree of freedom by employing VO2, and can find potential applications in future wireless THz communication systems as multi-channel filters, switches, spacers, logic gates and modulators.

Abstract-High power Continuously Frequency-tunable Terahertz Radiation Sources and Transmission Lines for DNP-enhanced NMR System

Diwei Liu, Tao Song,  Hao Shen,  Jie Huang, Ning Zhang, Chenghai Wang, Wei Wang, Shenggang Liu

https://ieeexplore.ieee.org/document/8510299

The effect of the electron beam quality of a 250GHz continuously frequency-tunable gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance is tuned by changing the operating voltage Vo or the operating magnetic field Bo on the operating frequency and the beam-wave interaction efficiency is investigated. Meanwhile, an improved transmission and mirror system with a well-focused Gaussian-like output beam is designed to match the DNP-NMR sample.

Abstract-Active control of broadband plasmon-induced transparency in terahertz hybrid metal-graphene metamaterial

Zhaojian Zhang, Junbo Yang, Xin He, Yunxin Han, Jingjing Zhang, Jie Huang, Dingbo Chen, Siyu Xu

https://128.84.21.199/abs/1806.00167v1

A hybrid metal-graphene metamaterial (MM) is reported to achieve the active control of the broadband plasmon-induced transparency (PIT) in THz region. The unit cell consists of one cut wire (CW), four U-shape resonators (USRs) and monolayer graphene sheets under the USRs. Via near-field coupling, broadband PIT can be produced through the interference between different modes. Based on different arrangements of graphene positions, not only can we achieve electrically switching the amplitude of broadband PIT, but also can realize modulating the bandwidth of the transparent window. Simultaneously, both the capability and region of slow light can be dynamically tunable. This work provides schemes to manipulate PIT with more degrees of freedom, which will find significant applications in multifunctional THz modulation.