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用a介质(n型掺杂GaAs)和b介质(TiO2)组成一含缺陷层的光子晶体。数值计算表明:此光子晶体在3.0~4.5THz范围内出现了5个透射率为1的缺陷模,这些缺陷模有如下特征:当n型掺杂GaAs的掺杂浓度n由1017/cm3增加到1019/cm3时,缺陷模的中心、半峰全宽度和透射率均保持不变,但若n增至1020/cm3,则缺陷模的透射率开始下降。入射角增加,缺陷模的透射率保持不变,但其中心发生蓝移,移动率为变量,且半峰全宽度变窄。a、b两介质或缺陷层c的几何厚度分别增加时,缺陷模的透射率和半峰全宽度分别保持不变,中心位置红移。这些现象为此类光子晶体实现太赫兹频段的梳状滤波提供了理论指导。
A medium (n-type doped GaAs) and b media (TiO2) constitute a defect-containing photonic crystal. Numerical calculations show that there are five defect modes with a transmittance of 1 in the range of 3.0-4.5 THz. These defects have the following characteristics: when the doping concentration n of n-type doped GaAs is increased from 1017 / cm3 to 1019 / cm3, the center of the defect mode, the full width at half maximum and the transmittance all remain unchanged. However, if n increases to 1020 / cm3, the transmittance of the defect mode begins to decrease. The incident angle increases and the transmissivity of the defect mode remains unchanged, but the blue shift occurs at the center, the mobility is a variable, and the full width at half maximum is narrowed. When the geometrical thicknesses of a and b medium or defect layer c increase respectively, the transmissivity and the full width at half maximum of the defect mode remain unchanged and the center position shifts red. These phenomena provide theoretical guidance for comb filtering of terahertz frequency band in these photonic crystals.