绝缘体-金属-绝缘体波导支持两种表面等离激元模式,即反对称模和对称模.反对称模的传播长度大,容易被激发.同时其模式尺度大,限制了器件的集成密度.对称模的模式尺度远小于反对称模,却难以被激发.为了应用对称模,提出了模式转换的理念.转换器根据变换光学被设计成均匀的各向异性介质.转换效率可接近80%. Insulator-metal-insulator waveguides support two types of surface plasmon modes, anti-symmetric and symmetric, which have large propagation lengths and are easily excited, while their mode size limits the integrated density of the device. The mode scale of the mode is much smaller than that of the anti-symmetry mode, but it is hard to be excited.In order to apply the symmetry mode, the concept of mode conversion is proposed.The converter is designed as a uniform anisotropic medium according to the transform optics, and the conversion efficiency can be close to 80%.