基于剪纸方法的一种可重构线极化转换空间序构超表面

Reconfigurable linear polarization conversion based on spatial-order kirigami metasurfaces

随着智能技术的发展,具有可调的电磁波极化转换器件对于实际应用来说至关重要.目前大多数基于PIN二极管、变容二极管来实现电可调,这些方法操作简单、实时性强,但仍存在平面序构调控自由度少、电路复杂、成本较高等问题.鉴于此,本文提出了一种基于剪纸结构的可重构极化转换超表面,通过调节折叠角度β改变磁偶极子之间的相互作用从而调谐极化转换工作频率,这种机械调控方法带来了更多调控自由度,且成本低廉、便于调控.为验证本文剪纸方法的可行性,基于非对称手性开口环谐振器设计了一款具有可重构空间序构的双频线极化转换超表面.实验结果表明,当β=10°,线极化转换器工作于5和5.8 GHz,当β变化到45°时线极化转换器工作频段调谐到5.8和7.2 GHz,平均频率调控范围达18.5%.此外,本文还分析了所提剪纸结构的泊松比和相对密度随β的变化规律,泊松比随着β增大而增大,且剪纸超表面的相对密度最小仅为未折叠情形下平面序构的1.5%.本文空间序构剪纸超表面为可重构线极化转换、多功能器件提供了新思路和新方法.

With the development of intelligent technology,it is essential to develop polarization-conversion devices with adaptable electromagnetic(EM) performance for practical applications.Up to now,most of attempts have relied on PIN diodes and varactor diodes for electrical tuning,typically featuring simplicity and timelineness.However,the shortcomings are also notable,such as less degrees of freedom(DoFs),more complex circuits and more expensive.In view of this,here we propose a kind of spatial-order metasurface for reconfigurable polarization conversion based on kirigami concept.By adjusting the folding angle β,the interaction between neighboring dipoles can be progressively changed and thus the operation frequency of polarization conversion can be shifted.Such a mechanical reconfigurable strategy brings about more DoFs for tuning and is cheaper and extraordinary convenient in practice.To verify the feasibility of our concept,a proof-of-concept spatial-order kirigami metasurface is proposed for the dual-band reconfigurable linear polarization conversion based on asymmetric chiral split ring resonators(SRRs).Experimental results show that the linear polarization operates at 5 and 5.8 GHz when folding angle is β=10°,these frequencies are shifted to 5.8 and 7.2 GHz when β=45°:a tuning range is expanded by 18.5%.In addition,the Poisson’s ratio and relative density of proposed kirigami metasurface as a function of β are also theoretically analyzed.The results show that the Poisson’s ratio increases with the value of β increasing.The relative density can be reduced to 1.5% of its unfolded planar counterpart.Our spatial-order kirigami metasurface strategy paves the way for implementing the reconfigurable linear polarization conversion and multifunctional devices.