Real-time tunable phase response and group delay in broadside coupled split-ring resonators
Real-time tunable phase response and group delay in broadside coupled split-ring resonators
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DOI：
10.1103/physrevb.99.245111
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发表时间：
2019-06
影响因子：
3.7
通讯作者：
Xiaoguang Zhao;Jingdi Zhang;K. Fan;G. Duan;J. Schalch;G. Keiser;R. Averitt;Xin Zhang
中科院分区：
文献类型：
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作者：
Xiaoguang Zhao;Jingdi Zhang;K. Fan;G. Duan;J. Schalch;G. Keiser;R. Averitt;Xin Zhang
控制电磁辐射的相位对于从通信到成像的应用范围是重要的。在这里，实时可重构的相位响应和群延迟的可调谐太赫兹超材料组成的双层宽边耦合开口环谐振器的演示。利用静电梳状驱动器，通过改变两层之间的横向距离来调整超材料的谐振频率，从而修改透射振幅和相位谱。在谐振频率附近，相位调制约为180 Ω。此外，当横向距离从0改变到时，基于使用卷积方法测量的频率响应，评估发射脉冲的群延迟（从-7到3 ps）中的显著调制。一个两端口谐振器模型，来自耦合模理论和有限元全波模拟的支持，揭示了调制的基本物理。具体而言，两层之间的耦合因子起着关键作用，其调整提供了一种途径，结构设计和优化。调谐相位响应和群延迟的能力使应用成为可能，例如太赫兹频率下的相位补偿和群延迟均衡。
Manipulating the phase of electromagnetic radiation is of importance for applications ranging from communication to imaging. Here, real-time reconfigurable phase response and group delay of a tunable terahertz metamaterial consisting of dual-layer broadside coupled split-ring resonators is demonstrated. Utilizing electrostatic comb-drive actuators, the metamaterial resonant frequency is tuned by changing the lateral distance between the two layers which modifies the transmission amplitude and phase spectrum. The phase modulation is approximately 180˚ in the vicinity of the resonant frequency. In addition, remarkable modulation in the group delay of transmitted pulses (from −7 to 3 ps) is evaluated based on the measured frequency response using the convolution method when the lateral distance is changed from 0 to. A two-port resonator model, derived from coupled-mode theory and supported by finite-element full-wave simulations, reveals the underlying physics of the modulation. Specifically, the coupling factor between the two layers plays a critical role, the tuning of which provides a route for structure design and optimization. The capability of tuning the phase response and group delay enables applications, such as phase compensation and group-delay equalization at terahertz frequencies.