In this work, we propose a method of achieving quasi-continuous linear phase gradient for transmitted waves based on conformal spoof surface plasmon polariton (SSPP). To this end, a SSPP structure with high transmission is firstly designed as the unit cell of the metamaterial. To obtain the phase gradient, SSPP structures are arranged delicately in a way that they are conformal to the brachistochrone curve. In this way, quasi-continuous linear Pancharatnam-Berry (PB) phase profile can be realized strictly along one of the two transverse directions. To verify this idea, a dual-band transmissive metamaterial operating in X and Ku band was designed, fabricated and measured. Due to the phase gradient imparted by the conformal SSPP structures, high-efficiency anomalous refraction can be realized within the two bands. Different from the general PGM, the phase gradient of the conformal SSPP structure allows us to achieve the desired anomalous refraction angle without reconstructing the PB phase. Both the simulation and measurement results are well consistent with theoretical predictions. This work provides another strategy of achieving anomalous refraction and may find applications in beam steering, digital beam forming, etc.

中文翻译：

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基于共形欺骗表面等离子体激元极化子的准连续线性相梯度超材料

在这项工作中，我们提出了一种基于共形欺骗表面等离子体激元极化子（SSPP）的透射波实现准连续线性相位梯度的方法。为此，首先将具有高透射率的SSPP结构设计为超材料的晶胞。为了获得相位梯度，SSPP结构以与腕管曲线一致的方式精心布置。以这种方式，可以严格地沿着两个横向方向之一来实现准连续线性潘查拉特南-贝里（PB）相轮廓。为了验证这一想法，设计，制造和测量了在X和Ku波段工作的双波段超材料。由于共形SSPP结构赋予的相位梯度，可以在两个波段内实现高效反常折射。与一般的PGM不同，保形SSPP结构的相位梯度使我们能够获得所需的异常折射角，而无需重建PB相。仿真和测量结果均与理论预测吻合良好。这项工作提供了实现异常折射的另一种策略，并且可能会在光束转向，数字光束形成等方面找到应用。