介质平面光波导TE0模模场分布的高斯近似

基于介质平面光波导端面无受限衍射场光束的光束传输因子的特点,阐明光波导TE0模模场分布采用高斯分布近似表达的合理性。基于场分布间的匹配效率计算公式,提出采用等效匹配效率方法确定用于高斯近似表达的等效模场半宽度,给出基于光波导芯层半宽度和归一化芯层驻波参量和归一化包层倏逝波参量表达的光波导等效模场半宽度的函数表达式,给出高斯近似分布与光波导本征场分布的匹配效率,阐明采用等效匹配效率方法确定等效模场半宽度的合理性。采用求解方程组的方法,给出基于光波导芯层半宽度和归一化频率表达的光波导等效模场半宽度的拟合函数表达式,并基于拟合引起的误差分析阐明了拟合函数表达式的精确性。

Gaussian Approximation for Mode Field Distribution of Dielectric Planar Waveguide TE0 Mode

Based on the characteristic of the beam propagation factor of the diffractive beam from the end surface of dielectric planar waveguide,the rationality of the Gaussian approximation for the mode field distribution of planar waveguide TE0 mode is clarified.As the computing formula of the matching efficiency between two field distributions is engaged,the method of equivalent matching efficiency is advanced for ascertaining the equivalent mode field half width of the Gaussian approximation expression,and the computing formula of equivalent mode field half width which is expressed by the half thickness of core layer,the normalized standing wave parameter of core layer and the normalized evanescent wave parameter of cladding layer of the planar waveguide are acquired,and the matching efficiency between the Gaussian distribution and the eigen mode field distribution of planar waveguide TE0 mode is presented.The rationality of the method of equivalent matching efficiency for computing equivalent mode field half width is explained.Finally,as the method of solving the equations is introduced,the fitting expression of equivalent mode field half width which is expressed by the half thickness of core layer and the normalized frequency of planar waveguide is suggested,and the accuracy of fitting expression is showed by the error analysis.