光子晶体能带与缺陷结构光子器件研究

发布时间：2018-10-11 15:59

【摘要】：光子晶体是由不同介电常数材料呈周期性分布的人工微纳结构。它具有独特的控制光子的能力,不仅出现了许多新奇的物理现象,如负折射、自准直、慢光效应,还可以设计实现光子晶体光纤、波分复用器、光开关、模式转换器、功率分配器、激光器等光子器件。在本论文中,我们深入挖掘光子晶体能带和缺陷结构的独特性质,并探究了光子晶体缺陷结构在光子器件方面的若干应用。首先,我们采用平面波展开法,系统研究了铜币形空气孔二维三角晶格光子晶体的完全带隙随结构参数变化而改变的规律。研究表明：铜币形散射子结合了两种类型的光子晶体(空气孔型和介质柱型)有利于获得更宽的完全带隙,该光子晶体大完全带隙对制备工艺上可能引起的材料掺杂和空气孔半径的偏离具有一定的稳定性。通过对参数的分组优化,发现在ε=22.75, R=0.483 um, d=0.195 um, (φ=90°, G=1.3时,完全带隙的宽度获得最大值0.1361(△ωα/2πc),带隙论为33.55%。接下来,我们研究了三端口光子晶体滤波器需要满足的品质因子比值条件和相位条件,以及提高品质因子特性的几种方法,设计了两款高性能的光子晶体滤波器。在前文三端口滤波器研究的基础上,我们利用二维正方晶格介质柱型光子晶体(PC),设计了一款新颖的多信道下路滤波器,该滤波器主要由四个线性渐变型微腔和异质结构光子晶体反射器组成。利用平面波展开法(PWE)以及二维时域有限差分法(2D-FDTD),分析了该异质结构滤波器的工作机制,并进一步探究了微腔参考面与异质结界面之间距离d对下路效率的影响。研究表明,该异质结反射器可以实现接近100%的反射,大幅度地提高了三端口滤波器的滤波效率。所设计的多信道滤波器各个通道都能有效地实现下路滤波功能,信道间隔10 nm,滤波效率都在90%以上,透射谱半高宽都在0.54 nm以下,达到较高的品质因子特性。该滤波器尺寸大小只有15.15μm×13.91μm,且滤波效率高,对未来光路集成具有好的应用前景。我们还研究了光子晶体的偏振无关波导,证实了在三角晶格空气孔光子晶体波导中能同时支持横电波(TE)和横磁波(TM)。采用遗传算法,找到了一组合适的结构参数使得TE导模与TM导模重叠。被优化的波导实现了偏振无关单模传输以及达到0.012(△ωα/2πc)的工作带宽。而且,在大部分频率范围内导模展示了大带宽的慢光特性和极低的群速度色散。
[Abstract]:Photonic crystals are artificial nanocrystalline structures with periodic distribution of materials with different dielectric constants. It has a unique ability to control photons. It not only has many novel physical phenomena, such as negative refraction, self-collimation, slow light effect, but also can be designed to realize photonic crystal fiber, wavelength division multiplexer, optical switch, mode converter. Power divider, laser and other photonic devices. In this thesis, we explore the unique properties of photonic crystal band and defect structure, and explore some applications of photonic crystal defect structure in photonic devices. Firstly, the complete band gap of two-dimensional triangular lattice photonic crystal with copper coin-shaped air holes is systematically studied by using the plane wave expansion method. It is shown that the combination of two types of photonic crystals (air holes and dielectric cylinders) is conducive to wider complete bandgap. The large complete band gap of the photonic crystal has a certain stability to the material doping and the deviation of the air pore radius which may be caused by the preparation process. By grouping optimization of parameters, it is found that when 蔚 = 22.75, rn 0.483 um, DX 0.195 um, (蠁 = 90 掳, G ~ (3), the maximum width of complete band gap is 0.1361 (蠅伪 / 2 蟺 c), gap theory is 33.55). Then, we study the quality factor ratio condition and phase condition of the three-port photonic crystal filter, and several methods to improve the quality factor characteristics. Two high performance photonic crystal filters are designed. Based on the study of three-port filter, we design a novel multi-channel down-path filter using two-dimensional square lattice dielectric cylindrical photonic crystal (PC),. The filter consists of four linear graded microcavities and a heterostructure photonic crystal reflector. Using the plane wave expansion method (PWE) and the two-dimensional finite-difference time-domain (2D-FDTD) method, the working mechanism of the heterostructure filter is analyzed, and the influence of the distance d between the microcavity reference plane and the heterojunction surface on the lower path efficiency is further explored. It is shown that the heterojunction reflector can achieve nearly 100% reflection and greatly improve the filtering efficiency of the three-port filter. Each channel of the designed multi-channel filter can effectively realize the function of down-channel filtering. The filtering efficiency of 10 nm, channel interval is above 90%, and the transmission spectrum half-maximum width is below 0.54 nm, which achieves a high quality factor. The size of the filter is only 15.15 渭 m 脳 13.91 渭 m, and the filter efficiency is high, so it has a good application prospect for the future optical path integration. We also study polarization-independent waveguides of photonic crystals. It is proved that both transverse wave (TE) and transverse magnetic wave (TM). Can be supported in triangular lattice air hole photonic crystal waveguides. Genetic algorithm is used to find a set of suitable structural parameters to make the TE guide mode overlap with the TM guide mode. The optimized waveguide achieves polarization independent single-mode transmission and bandwidth up to 0.012 (蠅伪 / 2 蟺 c). Moreover, in most frequency ranges, the guided mode exhibits the slow light characteristics of large bandwidth and extremely low group velocity dispersion.
【学位授予单位】：广西师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN713;O73

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