对于芯区为非线性介质、衬底及包层为线性介质的平板波导， 提出用多层分割法分析芯区的模场， 采用递推公式（等效于推广的传递矩阵法）求解传播常数与光功率间的依赖关系。该法适用于克尔型或非克尔型介质及芯区折射率非均匀的一般情形。实例计算结果与已有的精确数值计算结果十分符合。 In the case of slab waveguides with core as nonlinear medium, substrate and cladding as linear medium, a multi-layer segmentation method is proposed to analyze the mode field of the core region and the recursion formula (equivalent to the extended transfer matrix method) is used to solve the propagation constant Dependent on optical power. This method is suitable for Kerr-type or non-Kerr-type media and the core refractive index in the general case of non-uniform. The calculated results of the example are in good agreement with the existing accurate numerical results.