基于SPPs的方形凹环结构MIM滤波器设计

Design of the Square Concave Ring Resonantor MIM Filter Based on the Surface Plasmon Polaritons

基于表面等离子体波的传播特性提出了一种由方形凹环与波导管耦合而成的MIM结构滤波器,运用有限元法数值计算获得了该滤波结构的磁场分布、透射谱和共振波长分布曲线.研究结果表明,其阻带透射率最小透射比可低至0.01,通带最大透射比则高达0.96,并且顶部分布平滑.在增大滤波器波导结构参数I、H时,相应的透射谱线会有明显的红移,且不同模式阻带的透射比也会随之改变,此外共振波长与结构参数的变化呈现线性关系.在增大结构参数D时,模式1的透射率从之前的0.63增加到0.80,模式1最终消失,其余模式几乎不变,同时共振波长分布与参数D的变化无关.通过结构参数的优化,可以使波导结构的品质因数从14.82提升到17.07,通频带亦有所增加.该MIM结构滤波器具有封装尺寸小、多模式、阻带较窄、通带平滑、良好的品质因数以及可调节性,在微纳集成光学器件尤其是波分复用系统中有着良好的应用前景.

Based on the surface plasmon polaritons, a Metal-Insulator-Metal （MIM） structure filter which is coupled by a square concave ring resonantor and a waveguide is proposed . The magnetic field distributions, the transmission spectrums and the resonant wavelength distribution curves of the MIM structure are obtained through the numerical simulation software which is based on the finite element method. The results show that its stopband has a minimum transmittance of 0.01 while its passband transmittance can reach up to 0.96 and the top is smooth.When the parameter I or H of the waveguide structure is increased, the corresponding transmission curve has obvious red shift and the transmittance of different stopband modes will also change. In addition, the resonance wavelength shows a linear relationship with the structure parameters. When the structure parameter D is increased, the transmittance of mode 1 increases from 0.63 to 0.80, the mode 1 disappears eventually and the other modes are almost unchanged, the resonance wavelength shows no relationship with D. After optimization of structure parameters, the quality factor of waveguide structure can be improved from 14.82 to 17.07 and the bandwidth of the passband is increased. The MIM structure filters have the advantages of small footprint size, multi-modes, narrow stopband, smooth passband, good quality factor and adjustability. Therefore the MIM structure filters may have good applications in Micro-nano integrated optical devices,especially in wavelenth division muhiplexing system.