等效折射率模型分析二维光子晶体微谐振腔模态

Study of Two-dimensional Photonic Crystal Microcavities Based on the Effective-Index Model

采用数值计算方法,利用等效折射率模型研究不同折射率材料制造的二维光子晶体微谐振腔的模态。发现可以通过增加薄膜厚度达到良好的光子局域化。讨论了薄膜层材料折射率分别为n=3.42,2.50,1.80,1.60,薄膜层厚度分别对应为0.1529,0.2182,0.3341,0.4003μm,其等效折射率分别对应于2.81,2.23,1.52,1.38时,达到良好光子局域,说明介质材料与空气折射率差值小的光子晶体微谐振腔结构若要有好的光子局限能力,除了需要靠介质材料本身的全反射效应外,还需有足够厚的膜层厚度。从而找到一个能控制光场分布同时维持单模振荡的机制,揭示微谐振腔体薄膜层厚度对模态影响,为实际研制具有高质量微谐振腔提供了一种较好的预估手段。

The field-pattern of various resonant modes of two-dimensional photonic crystal microcavity structure is investigated using the effective-index model. Results show that increasing optical thickness can lead to good photon localization. The refractive index and optical thickness of materials are tested at various values of the refractive index, film thickness, and effective index to achieve good photon localization. The effect of optical thickness on the modal the resonance characters are analyzed. It is important to find a mechanism through which to control the optical-field distribution and maintain single-mode vibration on a large scale. A two-dimensional photonic crystal, which has periodically-distributed refraction coefficient, is proposed as a potential choice. This paper also indicates that for a photonic crystal structure with a small refractive index difference to acquire a good photon-restriction ability, it must not only rely on the total internal reflection generated in its own materials, but it also must employ an adequately thick layer of optically thick material. Through the above analysis, theoretical guidance has been provided for the design, preparation, and application of such photonic crystal micro-resonators.