Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China.
State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai, 200433, China.
Sci Rep. 2018 Jan 18;8(1):1051. doi: 10.1038/s41598-018-19611-8.
Although metamaterials wave-plates have been demonstrated previously, many of them suffer from the issue of narrow bandwidth since they typically rely on resonance principles and thus exhibit inevitable frequency dispersions. Here, we show that the dispersion of spoof surface plasmon (SSP) mode supported by a fishbone structure can be freely modulated by varying the structural parameters. This motivates us to establish a general strategy of building broadband wave-plates by cascading two fishbone structures with different propagation constants of SSP modes. We derive a criterion under which the cross-polarization phase-difference across the whole device can maintain at a nearly constant value over a wide frequency band, with frequency dispersions in the two fishbone structures cancelled out. As an illustration, we design and fabricate an efficient microwave quarter-wave plate and experimentally characterize its excellent polarization-control performances over a broad frequency band (7-9.2 GHz). Our findings can stimulate making dispersion-controlled high-performance optical functional devices in different frequency domains.
尽管超材料波片之前已经有过演示，但由于它们通常依赖于共振原理，因此不可避免地存在频率色散，因此其中许多都存在带宽较窄的问题。在这里，我们表明，鱼骨结构所支持的赝表面等离激元（SSP）模式的色散可以通过改变结构参数来自由调节。这促使我们通过级联两个具有不同 SSP 模式传播常数的鱼骨结构来建立宽带波片的一般策略。我们得出了一个准则，根据该准则，整个器件的交叉偏振相位差可以在很宽的频带内保持几乎恒定的值，两个鱼骨结构中的频率色散相互抵消。作为说明，我们设计并制造了一种高效的微波四分之一波片，并在很宽的频带（7-9.2GHz）内对其出色的偏振控制性能进行了实验表征。我们的研究结果可以激励在不同频率域中制造色散控制的高性能光学功能器件。
