Abstract We investigate the defect states arising in the Bragg and non-Bragg gaps by inserting a straight duct into a waveguide with periodically corrugated walls. In periodic waveguides, the Bragg gap is created by the interference of the same transverse modes whereas the different mode coupling leads to the non-Bragg one. Due to the involved high-order modes, there are two defect states observed in the non-Bragg gap while only one in the Bragg gap, indicating that transverse modes play a significant role in the creation of defect states. Furthermore, the frequency of each defect state highly relies on the defect geometries and their band widths can be optimized by the number of waveguide segments. The proposed transverse mode competition analysis reveals the mechanism of frequency shifting and provides an opportunity for guided wave control engineering, which would definitely benefit their applications in various functional devices, such as filters, sensors, and amplifiers.

中文翻译：

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波纹壁波导缺陷状态的横模竞争

摘要 我们通过将直管插入具有周期性波纹壁的波导来研究布拉格和非布拉格间隙中出现的缺陷状态。在周期性波导中，布拉格间隙是由相同横向模式的干涉产生的，而不同模式耦合导致非布拉格间隙。由于涉及高阶模式，在非布拉格能隙中观察到两种缺陷态，而在布拉格能隙中仅观察到一种，表明横向模式在缺陷态的产生中起着重要作用。此外，每个缺陷状态的频率高度依赖于缺陷几何形状，并且它们的带宽可以通过波导段的数量进行优化。