利用光频范围贵金属介电常量的虚部远小于其实部绝对值的特点,采用一阶微扰理论得到了对称金属包覆波导横电和横磁导模微扰传播常数的解析公式。针对金属包覆波导传输损耗大的缺陷,提出采用亚毫米尺度的超厚导波层来抑制传输损耗的新方法。微扰公式与精确数值解结果相符。 Based on the first order perturbation theory, the analytic formula of the perturbation propagation constant of the transversely and transversely permeating modes of a symmetric metal clad waveguide is obtained by using the feature that the imaginary part of the permittivity of the noble metal in the optical frequency range is far smaller than the absolute value of its real part. Aiming at the defect of large transmission loss of metal clad waveguide, a new method to suppress the transmission loss by using super thick conductive layer with submillimeter scale is proposed. The perturbation formula is consistent with the exact numerical solution.