【作者】 李海根；

【导师】 周治平；

【作者基本信息】 华中科技大学 ， 物理电子学， 2009， 硕士

【摘要】 光子晶体是一种新型的光学材料,它是由不同折射率的材料周期性排列而形成的人工晶体结构。它最显著的特征是光子带隙和局域特性,处于禁带中的光不能在光子晶体中传播。如果在完整的光子晶体晶格中引入缺陷,在原来的带隙中允许缺陷态存在。因此,在光子晶体中引入点缺陷、线缺陷,可形成光子晶体微腔和一维光波导,进一步利用这些缺陷以及它们的组合可以形成多种新型的光子器件。光子晶体有着十分广泛的应用领域,从微波通信、太赫兹器件到光子芯片,从通信器件、太阳能电池、生物化学传感到隐身技术,可以说,涵盖了光通讯、激光器、光子器件等非常广阔的领域。因此近年来对光子晶体的研究是如火如荼,其中之一就是光子晶体微腔的研究,在光子晶体中引入一个点缺陷,就会形成以点缺陷为中心的微谐振腔。本文阐述了光子晶体的研究现状及理论基础,根据能带理论自行设计了一种新型的光子晶体微腔结构,并首次通过调整与线缺陷波导紧邻的两排空气孔之间的间隔,达到调整折射率分布,从而得到异质结结构,将光约束在微腔中,同时考虑到传感的实际运用,在波导微腔中留有一放置被探测物的空气小孔。首先通过调整光子晶体波导宽度得到单模波导;然后设计模式间隙(mode-gap),同时根据布洛赫波与波导导模来设计反射镜(mirror)与喇叭口(taper)将光有效地约束在腔中;通过仿真,得出了微腔的谱响应和缺陷态模场分布;对缺陷态光谱曲线的分析得出Q值。进而对微腔结构参数对Q值的影响进行了分析。结果表明,我们的结构不仅可以保持较高的Q值,而且使结构简单、易耦合、工艺上易实现而且精度高,同时保持很小的尺寸,大约7.2μm×2.8μm,非常利于光电子器件的集成。最后,将上述光子晶体微腔应用于传感,结果表明中心波长对待探测物折射率扰动引起的漂移足够大,可以用于生物化学传感。更多还原

【Abstract】 Photonic crystal (PhC)is a kind of novel optical material, it is artificial periodic structure made of arrays with different constant. Its outstanding feature is photonic bandgap, light frequency located in which will be forbidden at all. If some“defect”is introduced in the perfect photonic crystal lattice, some defect state will be permitted in the original bandgap. So photonic crystal microcavity and one dimensional waveguide can be formed through introducing point defect and line defect respectively, and various optical devices can be made by using these defects and their combination.Photonic crystal has extensive applications, from microwave communication, terahertz devices to photon chips, from communication devices, sollar cell, biochemical sensor to stealth technology. It covers a very broad area including optical communication, lasers and photonic devices. Thus, study on photonic crystals becomes very hot recently, among which is photonic crystal microcavity, a micro-resonator formed by introducing a point defect in photonic crystal lattice.The recent progress on theoretical work of photonic crystal cavities are introduced in this thesis, and a novel microcavity based on photonic crystal is designed according to the photonic band theory. And it’s the first time to our knowledge to tune the two rows of air holes ajacent to the waveguide and a PhC heterostructure is obtained, thus confining light into the cavity. Considering the application for sensor, a smaller air hole in the middle of the structure is used to place analytes.First, single mode waveguide is got through tuning the width of the PhC waveguide, and then modegap is designed; meanwhile, mirror and tapre is designed according to the effective index matching of the bloch mode and the guided mode of the waveguide to confine light in the cavity effectively. The spectra response and the mode profile of the defect are obtained; Q value is obtained through the analysis of the defect spectra response. Furthermore, the influence of structure parameters on Q value are analyzed. The result shows that the structure proposed in this article is very simple, easy for coupling, easy to realize, and meanwhile maintaining higher Q value and smaller size compared to those structures mentioned in relevant documentations, about 7.2μm×2.8μm,very good for integration.The application of the above high Q PhC cavity in biochemical sensing is proposed. It has shown that the central wavelength shift of this high Q cavity is large enough for refractive index perturbation of the analyte.更多还原