Yang Liu, Zhou Yong Jin, Zhang Chao, Xiao Qian Xun
Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai, 200444, China.
Sci Rep. 2017 Oct 27;7(1):14237. doi: 10.1038/s41598-017-14708-y.
We demonstrate a novel route to control the filtering of spoof localized surface plasmons (LSPs) on the corrugated metal-insulator-metal (MIM) ring resonator. The spoof LSPs resonance modes can be effectively tuned to achieve broad passband (covering the quadrupole mode and the hexapole mode) by selecting proper lengths in the input and output coupling area. The mutual coupling between the input and output lines produces the flat-top transmission response and sharp out-of-band rejection. Compared with the wideband bandpass filters based on spoof plasmonic waveguides, the proposed filter is ultra-compact and only 0.35λ*0.35λ. In order to further improve the property of the bandpass plasmonic filter, all the out-of-band frequencies (the dipole mode and the octopole mode) have been rejected by introducing a shunt stepped-impedance resonator and double C-shaped rings on the back of the substrate of the filter. Simulated results are confirmed via experiment, showing good rejection and wideband filtering performance with low insertion loss, flat-top transmission response and sharp out-of-band suppression. The proposed filter can find more applications in the highly integrated plasmonic circuits and systems in both terahertz and microwave regimes.
我们展示了一种控制波纹金属-绝缘体-金属（MIM）环形谐振器上的伪局域表面等离子体激元（LSPs）滤波的新途径。通过在输入和输出耦合区域选择合适的长度，伪LSPs共振模式可以被有效地调谐以实现宽带通（覆盖四极模式和六极模式）。输入和输出线之间的相互耦合产生了平顶传输响应和尖锐的带外抑制。与基于伪等离子体波导的宽带带通滤波器相比，所提出的滤波器超紧凑，尺寸仅为0.35λ*0.35λ。为了进一步改善带通等离子体滤波器的性能，通过在滤波器基板背面引入一个并联阶梯阻抗谐振器和双C形环，所有带外频率（偶极模式和八极模式）都被抑制了。仿真结果通过实验得到了证实，显示出良好的抑制和宽带滤波性能，具有低插入损耗、平顶传输响应和尖锐的带外抑制。所提出的滤波器在太赫兹和微波频段的高度集成等离子体电路和系统中可以找到更多应用。
