Coupling between a point-defect cavity and a line-defect waveguide in three-dimensional photonic crystal
Coupling between a point-defect cavity and a line-defect waveguide in three-dimensional photonic crystal
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DOI：
10.1103/physrevb.68.235110
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发表时间：
2003-12-01
影响因子：
3.7
通讯作者：
Noda, S
中科院分区：
文献类型：
--
作者：
Okano, M;Kako, S;Noda, S
采用平面波展开法和三维时域有限差分法对三维光子晶体中点缺陷腔与线缺陷波导的耦合特性进行了理论研究。结果表明，对于对称结构的点和线缺陷是在同一个杆内的光子晶体，创建一个状态，其中的点和线缺陷模式是完全去耦由于模式对称性的失配，而耦合状态可以通过引入不对称性形成。在这些非对称结构中，通过估计点缺陷腔的品质因子，将点缺陷模式和线缺陷模式之间的耦合强度估计为线缺陷波导的端部的位置的函数。品质因数被发现振荡与波导的位置的小的变化。例如，品质因数以高达近似1.1x10（4）的因数变化，具有小的位置变化。此外，当光子晶体的尺寸是有限的，在实验的情况下，品质因数和光提取效率的估计。这些发现为控制光从点缺陷腔到线缺陷波导的传输提供了非常有用的设计规则。这些耦合结构被认为是三维光子晶体光路的重要组成部分。
The properties of the coupling between a point-defect cavity and a line-defect waveguide in three-dimensional (3D) photonic crystal are investigated theoretically using plane-wave expansion and 3D finite-difference time-domain methods. It is shown that for the symmetric structure where the point and line defects are on the same rod within the photonic crystal, a state is created in which the point- and line-defect modes are completely decoupled due to the mismatch in modal symmetry, while coupled states can be formed by introducing asymmetry. In these asymmetric structures, the strength of coupling between point- and line-defect modes is estimated as a function of the position of the end of the line-defect waveguide by estimating the quality factor of the point-defect cavity. The quality factor is found to oscillate with small changes in the position of the waveguide. For instance, the quality factor changes by a factor of up to similar to1.1x10(4) with small positional change. In addition, the quality factor and light extraction efficiency are estimated when the size of the photonic crystal is finite, as in experimental circumstances. These findings provide very useful design rules for controlling the transfer of light from the point-defect cavity to the line-defect waveguide. These coupling structures are thought to be an important component in 3D photonic crystal optical circuits.