准周期性对光子晶体缺陷模的影响

Effects of Quasi-Periodicity on Photonic Crystal Defect Modes

利用传输矩阵法研究了Bragg镜的准周期性对光子晶体缺陷模的影响。研究表明,无论是高折射率介质层还是低折射率介质层,当其折射率或厚度按一定的递变规律递增时,缺陷模都将向低频方向移动,递减时则向高频方向移动。但对缺陷模品质因子的影响却不同,高折射率介质层的折射率递增时品质因子提高,递减时品质因子减小;但低折射率介质层的折射率递变时品质因子的变化规律刚好相反;而介质层厚度的递变几乎不影响品质因子。此外还研究了准周期性对缺陷层内电场增强效应的影响。

By using the transfer matrix method, the effects of Bragg-mirror quasi-periodicity on the photonic crystal defect mode was studied. Investigations reveal that, for both high and low refractive-index dielectric layers, the defect mode always shifts in the direction of low frequency with the refractive index or thickness increasing gradually. However, the quality factor of the defect mode is affected in a different way by the quasi-periodicity. When the refractive index of the high refractive-index layer increases or decreases gradually the quality factor is correspondingly upgraded or lowered, but for the low refractive-index layer gradual change of the refractive index affects the quality factor in a reversed way, nevertheless gradual change of the layer thickness has almost no influence on the quality factor. Furthermore influence of the quasi-periodicity on the electric field enhancement effect inside the defect layer was also studied, which is similar to that on the quality factor.