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模场半宽是单模光波导的重要参数,它与众多的传输特性相联系.对于圆对称单模光纤,文献提出了两个著名的模场半径,并发现它们与光纤的众多传输特性相联系.对于单模平面波导,文献提出了高斯最小二乘拟合模场半宽的定义,文献提出了两种矩定义模场半宽——近场二阶矩和Laplace模场半宽,并导出它们和横向偏移损耗和角向偏移损耗的关系式,对阶跃对称单模平面光波导的TE_0模的计算表明:当偏移量较小时,用矩定义模场半宽算得的损耗将比用高斯最小二乘拟合模场半宽算得的更准确.本文首先导出了任意两不同对称单模平面光波导在高斯近似下的横向偏移和角向偏移损耗公式,接着用矩定义模场半宽直接代替高斯模场半宽得到了矩定义与连接损耗的关系式,最后以阶跃对称单模平面光波导的TE_0模为例进行了大量计算,结果发现当偏移量较小时,用矩定义和高斯最小二乘拟合模场半宽算得的损耗误差均较小,并且若两光波导厚度相差不大,归一化频率及偏移量均较小时,用矩定义算出的连接损耗比高斯近似准确.
Mode field half-width is an important parameter of single-mode optical waveguides, and it is related to a large number of transmission characteristics.For the circularly symmetric single-mode optical fiber, the literature proposed two well-known mode field radius, and found that they and the optical fiber transmission characteristics For the single-mode planar waveguide, the literature proposes the definition of the half-width of the Gaussian least-squares fitting mode field. In the literature, two kinds of moment modes are defined, which are the half-width-near field second-order moment and the Laplacian half- Derive them and the relationship between the lateral offset loss and the angular offset loss. The calculation of the TE_0 mode of the step-symmetric single-mode planar optical waveguide shows that when the offset is small, the half-width of the mode field is defined as the loss It will be more accurate than Gaussian least square fitting mode field half-width.Firstly, the formulas of transverse offset and angular offset loss of any two different symmetric single-mode planar optical waveguides under Gaussian approximation are derived, Defining the half-width of the mode field to directly replace the half-width of the Gaussian mode field, the relationship between the moment definition and the connection loss is obtained. Finally, a large number of calculations are carried out using the TE_0 mode of the step-symmetric single-mode planar optical waveguide as an example. Hours, defined by the moment and high And the half-width loss of the mode-field half-width fitting is small, and if the two optical waveguides have little difference in thickness and the normalized frequency and the offset are small, the connection loss calculated by the moment definition is smaller than the Gaussian approximation accurate.