Abstract-Photo-excited switchable broadband linear polarization conversion via asymmetric transmission with complementary chiral metamaterial for terahertz waves

Yonghzi Cheng, Hui Luo, Fu Chen, Xuesong Mao, and Rongzhou Gong

Fig. 1. Design schemes of the proposed compound CCMM: (a-c) the front, back and perspective views of the unit-cell structure, (d) three-dimensional (3D) array structure.

https://www.osapublishing.org/osac/abstract.cfm?uri=osac-2-8-2391

We present a photo-excited complementary chiral metamaterial (CCMM), which could realize a broadband dynamically switchable linear polarization conversion and asymmetric transmission (AT) effect for terahertz (THz) waves. The unit-cell structure of the photo-excited CCMM is composed of a bi-layer twisted complementary cut-wire (CCW) structure integrated with semiconductor photoconductive silicon (Si). The electric response of the photoconductive Si filled in the slot of the CCW structure can be tuned by the different pump optical power. The simulation results indicate that normal incident x(y)-polarization wave propagation along the -z (+z) axis direction pass through the CCMM without pump beam is converted into the y(x)-polarization wave, and the polarization conversion ratio (PCR) of over 90% and AT parameter of over 0.8 in the frequency range of 0.69-0.82 THz can be obtained. Furthermore, the broadband PCR and AT parameter can be tuned dynamically with the variation of Si conductivity by adjusting the pump power. Moreover, the surface current distributions of the unit-cell structure with different Si conductivity at the resonance frequency are discussed to illustrate its physics mechanism. Therefore, this work could offer a new platform for exploring dynamically tunable THz polarization controlling devices with photoconductive materials and have great prospects in various areas, such as terahertz imaging and wireless communication

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Based on graphene tunable dual-band terahertz metamaterial absorber with wide-angle

Mulin Huang, Yongzhi Cheng, Zhengze Cheng, Haoran Chen, Xuesong Mao, Rongzhou Gong,

https://www.sciencedirect.com/science/article/abs/pii/S0030401818300646

We present a wide-angle tunable dual-band terahertz (THz) metamaterial absorber (MMA) based on square graphene patch (SGP). This MMA is a simple periodic array, consisting of a dielectric substrate sandwiched with the SGP and a continuous metallic film. The designed MMA can achieve dual-band absorption by exciting fundamental and second higher-order resonance modes on SGP. The numerical simulations indicate that the absorption spectrum of the designed MMA is tuned from 0.85 THz to 1.01 THz, and from 2.84 THz to 3.37 THz when the chemical potential of the SGP is increasing from 0.4eV to 0.8eV. Moreover, it operates well in a wide-angle of the incident waves. The presented THz MMA based on the SGP could find some potential applications in optoelectronic related devices, such as sensor, emitter and wavelength selective radiators.