Abstract-Multi-mode graphene based terahertz amplitude modulation enhanced by hollow cross H-structured metasurface

Physica Scripta

Liangping Xia, Yixuan Zou, Man Zhang, Wenjuan Yan, Suihu Dang, Songbai Li, Shaoyun Yin,  Hongliang Cui

https://iopscience.iop.org/article/10.1088/1402-4896/ab1bfe/pdf

A graphene-metasurface based THz amplitude modulator enhanced with the hollow cross H array in a metal film is proposed. Based on the transmission line theory, the equivalent analysis model of the modulator is built. With the model, the multi-mode resonation excited by the metasurface is analyzed and the amplitude modulations of the THz transmission are discussed. By applying modulation voltage between the metallic metasurface and graphene film in the experiment, three enhanced modes in the transmission spectrum are observed and the maximum modulation depth is enhanced to 49.3% in the band of 0.1-1.8THz. The experimental results exhibit a good agreement with the theory analysis.

Abstract-A near-perfect THz modulator enabled by impedance matching method with VO2thin films

Liang-Hui Du, Hong-Fu Zhu,  Jiang Li, Qi-Wu Shi,  Li-Guo Zhu

https://ieeexplore.ieee.org/document/8510388

We present a terahertz (THz) amplitude modulator with near perfect modulation depth based on the impedance matching method during the thermally induced insulator-metal transition (IMT) of VO 2 thin films. It has been observed that the impedance matching-induced THz amplitude modulation was sensitive to the resistance switching characteristics of the VO 2 thin films. With four orders of change in resistance of the properly designed VO 2 films during the IMT, we experimentally achieved a near perfect THz modulator with an intensity modulation depth of 99.7 % between the insulator phase of VO 2 and the impedance matching state, and intensity modulation depth of 99.94% between the impedance matching state and the metallic phase of VO 2 . The experimental results were well explained by numerical simulations based on the transfer matrix model.