We numerically analyze two-dimensional photonic crystal (PhC) nanocavities on glass with a thin glass film on top of the structure. We investigated a multistep heterostructure GaAs PhC nanocavity located on glass. We found that covering the structure even with a very thin glass film efficiently suppresses unwanted polarization mode conversion occurring due to the asymmetric refractive index environment around the PhC. We also uncovered that the glass-covered structure can exhibit a higher Q factor than that observed in the structure symmetrically cladded with thick glass. We point out that the mode mismatch between the PhC nanocavity and modes in the upper glass film largely contributed to the observed Q-factor enhancement. These observations were further analyzed through the comparison among different types of on-glass PhC nanocavities covered with thin glass films. We also discuss that the in-plane structure of the upper glass film is important for additionally enhancing the Q factor of the nanocavity.

中文翻译：

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具有上玻璃薄膜的玻璃上的高 Q 二维光子晶体纳米腔

我们对玻璃上的二维光子晶体 (PhC) 纳米腔进行了数值分析，结构顶部有一层薄玻璃膜。我们研究了位于玻璃上的多步异质结构 GaAs PhC 纳米腔。我们发现，即使用非常薄的玻璃膜覆盖该结构，也能有效抑制由于 PhC 周围的不对称折射率环境而发生的不必要的偏振模式转换。我们还发现，玻璃覆盖的结构可以表现出比对称覆盖厚玻璃的结构更高的Q因子。我们指出，PhC 纳米腔与上层玻璃膜中的模式之间的模式不匹配很大程度上导致了观察到的Q因子增强。通过比较不同类型的覆盖有薄玻璃膜的玻璃上光子晶体纳米腔，进一步分析了这些观察结果。我们还讨论了上玻璃膜的面内结构对于额外提高纳米腔的Q因子非常重要。