各向异性左手材料平面波导TE模的传输特性

Propagation Properties of TE-guided Modes in a Slab Waveguide with Anisotropic Metamaterials

摘要:

对芯层为左手材料而覆盖层和衬底均为不同普通材料的三层平面波导进行了探讨。考虑损耗、色散和各向异性的左手材料, 利用TE模的色散方程, 结合模阶数、波导厚度以及电磁衰减系数的变化, 画出了相关的色散曲线和损耗曲线。根据这些曲线, 发现对于TE2模, 在频率为4.03GHz附近, 波导厚度为5mm, 它有非常大的有效折射率(接近80);当频率从4.0GHz增加到6.0GHz, 色散曲线的斜率为正、零和负。正斜率为正常色散, 负斜率为反常色散, 零斜率则群速为零。对于高阶TE模, 当频率为4.03GHz时, 它的损耗是最大的;当频率超过5.0GHz后, 波导厚度以及电磁衰减常数的变化对TE模的损耗特性影响不大, 这些新特性为制备小型化的波导器件提供了理论基础。

Abstract:

A three-layer slab waveguide with metamaterials as the core layer and the conventional materials as the cover and substrate was investigated. From a dispersive equation of TE modes, considering both loss and dispersion for the anisotropic metamaterials, related dispersive curves and loss curves were ploted depending on the mode number, waveguide thickness and damping constant. Based on these curves, it is found that, for the TE2 mode, at the frequency of 4.03GHz and waveguide thicknes of 0.5mm, it realizes an ultrahigh effective-refractive index (near 80);as the frequency increases from 4.0GHz to 6.0GHz, their slopes of the dispersive curves change from positive, zero to negative. The positive ones mean a normal dispersion while the negative ones are abnormal dispersion and zero one denotes zero group velocity. Besides, for the high order TE mode, as the frequency equals to 4.03GHz, its loss is the biggest. As the frequency increases and exceeds 5.0GHz, the loss is independent of the waveguide thickness and the damping constant.