Kim Daeik, Nguyen Mai Anh, Byun Gangil, Lee Jongwon
Department of Electrical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
Nanophotonics. 2023 Mar 31;12(13):2397-2403. doi: 10.1515/nanoph-2022-0752. eCollection 2023 Jun.
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.
非线性频率混频为在传统技术难以达到的频率范围内产生新的电磁源提供了一种替代方法。为了同时使用基频泵浦光束和在同一通道中产生的多个谐波信号，需要一种能够分离每个频率分量的装置。在此，我们提出并通过实验证明了基于超表面的泵浦频率和多个谐波频率的空间滤波器。该超表面是使用八个不同的基于裂环谐振器的相位元件设计的，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谐波和五次谐波频率（15和25GHz）处产生具有不同波束转向角的交叉极化反射波，并在5GHz基频下作为金属镜工作。我们的工作提出了一种新方法，能够基于非线性频率混频同时使用宽带多频源。
