摘要
光子晶体是光学与凝聚态物理交叉的新领域,也是近年来应用物理学的一个重要研究领域,它是一种由介电常数高的(低的)介质在另一种介电常数低的(高的)背景介质中周期排列所组成的人造多维周期结构材料,能够产生光子带隙。频率落在带隙内的光在晶体里沿任何方向都不能传播,因而具有能够抑制原子、分子的自发辐射等诱人的光电子学特性,在基础研究和实际应用上都有着巨大的潜力。本文在这一领域里进行了富有成效的研究,获得了很好的结果。主要有:(1)利用平面波展开方法来计算二维光子晶体的带隙结构。首先,我们设计正方晶胞的二维光子晶体模型。设x3方向为介质柱的轴方向,二维周期结构在x1-x2平面上。晶胞的晶格常数为a,半径为r,介质柱和空气柱的介电常数分别为εa=17和εb=1,a>2r。设计的核心思想是通过降低光子晶体结构的对称性,消除光子能带在晶体的布里渊区高对称点上的本征简并。(2)对于二维光子晶体的电磁波理论及周期介质中的Bloch波解做了详细的推导,给出了光子晶体中禁带存在的理论依据。同时以正方格子晶格的二维光子晶体为例,验证了电介质在空气圆孔中的排列存在E偏振和H偏振的光子带隙重叠区,称为绝对光子带隙。对于二维的光子晶体,两种本征偏振模式的光子能带结构可以独立地调节。
Photonic crystal is a new field which combines optics and condensed matter physics. It is also a great important research field of applied physics i n recent years.This is an artificial multidimension periodic structure i n the two background media which possess different dielectric constants. It is so cal led beca use its structure and characteristics resemble that of solid crystal. Photonic b and gap (PBG) struc ture is a periodic modulation of dielectric and it can exhibit 'forbidden' fre qu ency regions where electromagnetic waves can not propagate along any directions in the crystal. This may bring about some peculiar physical phenomena, as well a s wide applications in several scientific and technical areas. Some great a chievements made in this paper are listed as follows.(1) PBG structures with absolute band gaps are designed via the calculation of photonic band structures by planewave expansion method. A twodimensional ph otonic crystal is periodic along two of its axes and homogeneous along the third . A typical specimen, consisting of a square lattice of dielectric columns is sh own in Fig1. For certain values of the column, spacing this crystal can have a photonic band gap in the x1-x2 plane.The rods forming photonic crystal are characterized by a dielectric constant εa =17,they are embedded in a background medium whose dielectric constant is ε b=1 .The rods are of circular crosssection with radius r and the lattice c onstant of the square lattice is a with a>2r.The main idea is to lift the band degeneracy at high symmetry points in the Bril louin zone of crystals by lowering the structure symmetry of crystal.(2) It also gives a complete deduction for the electromagnetic wave theory of p hotonic crystal of two dimensions and Bloch wave solution in stratified periodic dielectric, offers the academic foundation of the existence of stop band, and for an example of two dimensional photonic crystal o
出处
《发光学报》
EI
CAS
CSCD
北大核心
2003年第2期125-129,共5页
Chinese Journal of Luminescence
基金
国家自然科学基金资助项目(60168001)
