Modulation of Junction Defects Created by Crossing Photonic Crystal Waveguides

In optical circuits, functional elements are often placed on waveguide junctions. We show that a junction in photonic crystals （PCs） possesses localized modes very close to the bandpass of waveguides. Their mode reso- nances and field patterns can be controlled by modulating the PC waveguides. It is expected that functions such as switching and routing could be developed naturally by using junction modes without any special design of microcavities. Our calculation results can be explained by the coupled mode theory.     

超大长宽比U型开口谐振器的太赫兹调控特性

近年来,金属亚波长结构由于在负折射材料方面存在巨大应用价值,及可作为太赫兹波段的光学限制器等器件应用,引起了研究者们的广泛关注。本文采用电子束曝光离子束刻蚀的方法在金膜上制备了亚波长的超大长宽比U型开口矩形谐振器阵列结构,利用时域有限差分方法(FDTD)和太赫兹时域光谱技术(THz-TDS)对U型阵列结构的太赫兹波透射光谱响应进行了测量和分析,讨论了透过率对结构几何参数的依赖特性和异常透射的物理机制。通过这种U型开口谐振器能够实现太赫兹波的强局域和场增强,可将太赫兹波局域在波长千分之一的尺寸上,从而实现了太赫兹的异常透射现象,这种超大长宽比的U型开口谐振器可在太赫兹探测、太赫兹成像及其他光学器件的设计上得以应用。