Song Hao, Sun Lei, Wang Guo Ping
Opt Express. 2020 Jan 6;28(1):753-759. doi: 10.1364/OE.382965.
A magnetic mirror operating in the terahertz band is designed based on the functional reflective metasurface, which is simply constructed by a one-dimensional periodic lithium tantalate micro cylindrical rod array on a Teflon substrate coated with a metal layer at the bottom and reflects the incoming electric field with a zero-phase change. Magnetic dipole resonance of the micro cylindrical rods excited in the metasurface is attributed to the perfect magnetic mirror at the frequency of 0.286 THz with the reflectivity of R = 0.98 for a normal incident electromagnetic wave. By real-time varying the direction from normal (0) to 28.45 degrees and the frequency from 0.286 to 0.382 THz of the incident wave, the metasurface can still behave as a perfect magnetic mirror with the reflectivity as high as 0.99. Most interestingly, in this case, the metasurface possesses the property of a retroreflector that the reflected wave returns along the direction of the incident wave, which is consistent with the grating equation. The tunable perfect magnetic mirror effect and the retroreflector property may provide ways in novel photonic devices and sensing applications.
基于功能性反射超表面设计了一种太赫兹波段的磁镜，该超表面由一维周期性钽酸锂微圆柱棒阵列简单构建而成，该阵列位于底部涂覆有金属层的聚四氟乙烯衬底上，能够以零相位变化反射入射电场。超表面中激发的微圆柱棒的磁偶极子共振在0.286太赫兹频率下产生了完美磁镜效应，对于垂直入射的电磁波，反射率R = 0.98。通过实时改变入射波从垂直方向（0）到28.45度的方向以及从0.286到0.382太赫兹的频率，该超表面仍可表现为反射率高达0.99的完美磁镜。最有趣的是，在这种情况下，超表面具有后向反射器的特性，即反射波沿入射波方向返回，这与光栅方程一致。这种可调谐的完美磁镜效应和后向反射器特性可能为新型光子器件和传感应用提供途径。
