Study of different spectral regions and delay bandwidth relation in slow light photonic crystal waveguides.
Study of different spectral regions and delay bandwidth relation in slow light photonic crystal waveguides.
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DOI：
10.1364/oe.18.026965
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发表时间：
2010-12
期刊：
影响因子：
3.8
通讯作者：
Hamza Kurt;K. Ustun;L. Ayas
中科院分区：
文献类型：
--
作者：
Hamza Kurt;K. Ustun;L. Ayas
研究了慢光在具有不同光谱特性的单模光子晶体波导中的传输，这些特性包括：常群折射率、高带宽和低群速度色散。通过调节边界孔的大小，波导模式的形式发生了显著变化，并跨越了三个不同的光谱区间。即，带隙导模的斜率朝向布里渊区边缘从负到正改变符号。在两者之间存在过渡区域，其中模式具有几乎为零的斜率。最大群折射率发生在这些转折点，以牺牲高色散和窄带宽为代价。系统地揭示了群指数和带宽之间的明显的权衡关系。我们发现，随着最里面的孔的半径增加到一定值以上，前者减少，后者增加都呈指数，但有不同的比例。平均组索引和带宽的乘积被定义为品质因数，其在详细的参数搜索之后达到大约0.30的值。通过时域有限差分研究证实了平面波展开法得到的频域分析结果。
We investigate slow light propagation in monomode photonic crystal waveguides with different spectral features such as constant group index, high bandwidth and low group velocity dispersion. The form of the waveguide mode alters dramatically and spans three different spectral intervals by tuning the size of the boundary holes. Namely, slope of the band gap guided mode changes sign from negative to positive toward the Brillouin zone edge. In between there is a transition region where modes have nearly zero slopes. Maximum group index occurs at these turning points at the expense of high dispersion and narrow bandwidth. The apparent trade-off relationship between group index and bandwidth is revealed systematically. We show that as the radius of the innermost hole is increased above a certain value, the former one decreases and the latter one increases both exponentially but with a different ratio. The product of average group index and bandwidth is defined as a figure of merit which reaches up to a value of approximately 0.30 after a detailed parametric search. The findings of the frequency domain analysis obtained by plane wave expansion method are confirmed via finite-difference time-domain study.