一维光栅结构中电场分布的计算分析

Computation and analysis of electric field distribution in one-dimensional gratings

光栅中的电场分布对光栅的激光损伤阈值具有重要影响,为此提出了一种计算一维光栅结构中电场分布的方法,该方法对于任意深度和占空比的光栅,均能计算得到光栅内外的电场分布.采用解析方法推导得到了计算公式,由于矩阵中元素值太小而无法求逆矩阵,应用基于增强透射矩阵的耦合波理论,并对其计算过程进行了改进,改进方法能够直接计算得到单层光栅的电场分布.进一步将该方法运用到多层光栅结构中,能够计算光栅和介质多层薄膜混合结构的电场分布.计算结果表明,采用该方法能够直接分析计算介质反射光栅内的电场分布,不仅可以获得精确解,而且可以大大降低计算量.

The distribution of electric field intensity in gratings has an important influence to the laser damage threshold of gratings. A calculation method of electric field distribution in one-dimensional gratings was presented, by using which the electric field distribution inside and outside the gratings could be calculated for arbitrary depth and duty cycle. The calculation equations were deducted using analytical method. Because of the values of the matrix elements are too small to calculate the anti-matrix, the rigorous coupled wave analysis based on an enhanced transmittance matrix was applied and the calculation process was improved. In this way, the electric field distribution of single gratings can be directly calculated. Extending this method to multilayer grating structures, the electric field distribution of hybrid structures of grating and thin films can be simulated. This method can analyze and calculate the distribution of electric field in the dielectric reflection gratings, and can get precise results and significantly reduce the calculation time.