A Tunable Graphene 0-90° Polarization Rotator Achieved by Sine Equation Voltage Adjustment.

Jinsong Dai,Qiyuan Lin,Lin Zhao,Zhongchao Wei,Yuyao Lou

doi:10.3390/nano9060849

Abstract

Polarization Manipulation has been widely used and plays a key role in wave propagation and information processing. Here, we introduce a polarization rotator in the terahertz range with a polarization conversion ratio up to 99.98% at 4.51 terahertz. It has a single graphene layer on top of the structure patterned by 45° tilted space elliptical rings. By changing the Fermi level from 0.3 ev to 0.7 ev of the graphene, we can turn the reflective light polarization direction between 0° to 90° with nearly unique magnitude. Surface currents theories and graphene characteristics clarify the relationship between polarization angle and Fermi level to be a sine equation adjusted voltage. We firstly put forward an equation to thetunable graphene changing the reflective light polarization angle. It can be widely used in measurement, optic communication, and biology. Besides, with nearly the unique reflective light in different directions, the rotator is designed into a novel radially polarization converter. The latter can be switched from radially polarized light to linearly polarized light, and vice versa, in the terahertz region.

Highlights

Various periodic metasurface applications achieved absorption [1,2], filter [3], sensing [4] and polarization conversion [5]
Ultra-broadband, wide-angel polarization converters [11,12,13,14] have been put forward to achieve a high polarization conversion ratio (PCR). Their converters are focused on x- to y- direction polarization conversion and expressed about the little reflective light, which is between the x- and y- polarization directions
Fan et al proposed a polarization rotator [16] which may change polarization direction by rotating the structure, electrical adjustment instead of structure rotation is produced in this work for polarization conversion in terahertz region

Summary

Introduction

Various periodic metasurface applications achieved absorption [1,2], filter [3], sensing [4] and polarization conversion [5]. Due to the advantages of the graphene, various manipulating devices included polarization converters. Their converters are focused on x- to y- direction polarization conversion and expressed about the little reflective light, which is between the x- and y- polarization directions. Chen et al proposed that they can change the polarization angle from 0◦ to 90◦ [15].

Results

Conclusion