Dynamic Reflection Phase Modulation in Terahertz Metamaterial

Zeng Yangjian,Li Qi,Su Xin,Yu Hongbin,Feng Chuhuan

doi:10.1109/jphot.2019.2926499

Zeng Yangjian, Li Qi + Show 3 more

Open Access

https://doi.org/10.1109/jphot.2019.2926499

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Abstract

In order to provide the terahertz metamaterial with dynamic phase modulation capability, a new strategy is proposed. It consists of two different unit cells involving particularly designed metallic concentric circular split ring resonators, both of which can be controlled with integrated pneumatic actuator and the resultant reflection phase modulation over 320° can be achieved. Based on this concept, a phase gradient metamaterial is designed and dynamic manipulation of the anomalous reflection from 12.3° to −12.5° for normal incidence has been successfully obtained. Moreover, a reflective metalens with 3.15 mm diameter based on current phase tunable metamaterial is also proposed and the dynamic focal length tuning from 0.91 to 2.32 mm has also been demonstrated.

Highlights

Metamaterials are artificially constructed electromagnetic (EM) materials and media with engineered electric permittivity and magnetic permeability [1], which can be obtained through structuring natural materials, such as metals, semiconductors and insulators
In order to provide the terahertz metamaterial with dynamic phase modulation capability, a new strategy is proposed. It consists of two different unit cells involving designed metallic concentric circular split ring resonators, both of which can be controlled with integrated pneumatic actuator and the resultant reflection phase modulation over 320° can be achieved
There are two phase modulation mechanisms for metamaterials – propagation phase and geometric phase, which are used to control the phases of incidence with linear and circular polarization, respectively

Summary

Introduction

Metamaterials are artificially constructed electromagnetic (EM) materials and media with engineered electric permittivity and magnetic permeability [1], which can be obtained through structuring natural materials, such as metals, semiconductors and insulators. For the linearly polarized incident wave, a propagation phase will be generated and the phase modulation can be achieved through adjusting the geometric parameters of the periodic unit cells of the metamaterial [21], [27]. [32] adopts a dynamical and continuous phase modulation method by employing voltage-controlled varactor integrated into the resonating meta-atoms operating at microwave frequencies. Designed metallic structure is integrated into our previously developed pneumatic actuator [34]–[37], constructing the unit cell of metamaterial. The geometry of the metallic structure will be changed, under the effect of which more than 320° dynamic phase modulation for the reflective EM wave can be achieved. Through dynamically controlling the phases of individual components, manipulation of the plane wave reflection and the spherical wave focusing have been successfully obtained, respectively

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