Nonlinear frequency mixings have shown an alternative way to create new electromagnetic sources in frequency ranges that are difficult to access with conventional techniques. To simultaneously use the fundamental frequency pump beam and multiple harmonic signals generated in the same channel, a device capable of separating each frequency component is required. Here, we propose and experimentally demonstrate metasurface-based spatial filters for the pump frequency and multiple harmonic frequencies. The metasurface was designed using eight different split ring resonator-based phase elements with 45° phase spacing, which allows wavefront shaping. The metasurface designed to have a one-dimensional gradient phase array produces cross-polarized reflection waves with different beam steering angles at the third- and fifth-harmonic frequencies (15 and 25 GHz) and operates as a metallic mirror at the fundamental frequency of 5 GHz. Our work suggests a new method to enable simultaneous use of broadband multi-frequency sources based on nonlinear frequency mixing.

中文翻译：

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用于多谐波信号的超表面空间滤波器

非线性混频显示了一种替代方法，可以在传统技术难以访问的频率范围内创建新的电磁源。为了同时使用同一通道中产生的基频泵浦光束和多个谐波信号，需要能够分离每个频率分量的装置。在这里，我们提出并通过实验证明了基于超表面的泵浦频率和谐波频率空间滤波器。超曲面的设计使用了八个不同的基于开口环谐振器的相位元件，相位间距为 45°，可实现波前整形。设计为具有一维梯度相位阵列的超表面在三次和五次谐波频率（15 和 25 GHz）下产生具有不同光束转向角的交叉极化反射波，并在基频为 5 时作为金属镜运行千兆赫。我们的工作提出了一种新方法，可以同时使用基于非线性混频的宽带多频源。