本文设计了一种带有两个水平侧耦合Fabry-Perot (FP)共振腔的基于金属-绝缘体-金属(MIM)结构的Y型表面等离子体光波导结构。传输谱存在一个较窄的阻带，两个腔的长度相同时，两个输出端的传输谱几乎完全重合；两个腔长度不同时每个输出端的传输谱上的阻带位置也不同，并且当一个输出端透射率达到最小时，另一个输出端的透射率接近最大。通过调节两个FP共振腔的长度、宽度以及腔内介质的折射率，可以调节表面等离子体激元在腔内发生共振从而形成驻波的工作波长，实现探测灵敏度高达1280 nm/RIU、品质因子大于200的传感特性。利用这些特性可以在两个输出端对不同的工作波长实现滤波、开关、分束等功能，因此这种亚波长表面等离子体光波导结构在集成光学滤波器、纳米光开关、分束器以及折射率传感器等领域有一定的应用前景。

A plasmonic Y-shaped metal-insulator-metal (MIM) plasmonic waveguide with two side-coupled Fab-ry–Perot (FP) resonant cavities is proposed. Simulation results show that there is a stopband existing in the transmission spectrum of each output port. When the lengths of the two cavities are equal, the transmission spectra of the two output ports are almost coincident. But if they are not equal, the two stopbands are not in the same place. Meanwhile, the transmission dip of one output port corresponds to the transmission peak of another port. By adjusting the length, width and refractive index of the two FP cavities, one can control the resonant wavelength of each cavity to further achieve functions of filtering, power splitting, switching and refractive index sensing. Results show that the sensing sensitivity is up to 1280 nm/RIU with its figure of merit above 200 when the waveguide is used as a refractive sensor. The proposed waveguide structure has potential applications in the fields of integrated optical filter, nano-optic switch, power splitter and refractive sensor in subwavelength scale.