Tunable group delay in a doubly resonant metasurface composed of two dissimilar split-ring resonators
Tunable group delay in a doubly resonant metasurface composed of two dissimilar split-ring resonators
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DOI：
10.1364/josab.36.002694
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发表时间：
2019-09
期刊：
影响因子：
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通讯作者：
Y. Tamayama;Yutaro Kida
中科院分区：
文献类型：
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作者：
Y. Tamayama;Yutaro Kida
我们开发了一种使用双谐振超表面连续控制电磁波群延迟的方法。该方法基于(i)具有两条谐振线的介质中的群速度对谐振线宽的依赖性，以及(ii)由开环谐振器组成的超表面的谐振线宽对电磁波的入射角的依赖性。为了验证这种群延迟控制方法，我们设计了由两个具有不同谐振频率的开环谐振器组成的太赫兹超表面，并对超表面的传输特性进行了数值分析。斜入射时观察到双谐振线，并且随着入射角的增加，谐振传输谷变得更深更宽。发现双谐振线中心频率附近的群延迟随着入射角的变化在大约0秒到20倍入射波周期的范围内变化。与之前报道的使用类电磁感应透明超材料对群延迟进行可变控制的方法相比，在小群延迟条件下实现了高透射率。
We develop a method to control the group delay of electromagnetic waves continuously using a doubly resonant metasurface. The method is based on the dependences of (i) the group velocity in a medium featuring two resonance lines on the resonance linewidths and (ii) the resonance linewidth of a metasurface composed of split-ring resonators on an incidence angle of electromagnetic wave. To verify this method for group-delay control, we design a terahertz metasurface composed of two split-ring resonators with different resonance frequencies and numerically analyze the transmission characteristic of the metasurface. Double resonance lines are observed for oblique incidence, and the resonance transmission dips become deeper and broader with increasing the incidence angle. The group delay at around the center frequency of the double resonance lines is found to vary in the range from about 0 s to 20 times the period of the incident wave with the incidence angle. In contrast to a previously reported method for variable control of group delay using electromagnetically-induced-transparency-like metamaterials, a high transmittance is achieved for a small group delay condition.