设计了一种含有矩形槽(RG)的方环谐振器边耦合金属-介质-金属(MDM)波导,运用Fabry-Perot(F-P)理论精确推导了谐振器的有效长度,并利用该结构实现了多模可调等离子体滤波器。在数值计算和理论分析的基础上,得到了除传统整数模式以外的非整数模式。非整数模式的波长随着RG长度的增加发生红移,这是因为RG位于磁场的波腹时,对磁场的影响最大;整数模式由于对RG不敏感,其波长保持不变,这是因为RG位于磁场的波节时,对磁场的影响最小。可以通过改变RG的形状、位置及数目来调控模式的数目和场分布。与传统的谐振器相比,所提结构和所得到的结果可以为灵活调控谐振波长提供更多选择,在光电子器件的设计上具有潜在的应用价值。

In this study, we design a metal-dielectric-metal (MDM) waveguide side-coupled square ring resonator with a rectangular-groove (RG). Its effective length is accurately derived through the F-P theory and a tunable multimode plasmonic filter is realized based on this structure. Based on numerical calculations and theoretical analysis, the extra non-integer resonant modes are obtained beyond the conventional integer modes. The wavelength of each non-integer resonant mode red-shifts with the increase of the RG's length because RG has the maximal effect on the magnetic field when it is located at antinodes of the magnetic fields. However, the integer modes are not sensitive to RG and their wavelengths are fixed because RG has the minimal effect on the magnetic field when it is placed on the nodes of the magnetic fields. The number of modes and their field distributions can be adjusted by changing the shape, position, and number of RGs. Compared with the conventional resonators, the proposed structure and the corresponding results are extremely useful for the design of optoelectronic devices as they can provide more channels to flexibly manipulate the resonant wavelengths.