提出一种新型的由T形与圆形谐振腔组成的光学滤波器, 并利用二维有限元法研究了它的特性。仿真结果显示, 当这两个腔在共振峰附近处于失谐状态时, 会产生电磁诱导透明现象; 同时, 由于两个腔的透射谱形是不同的, 所以当改变圆形腔的半径或T形结构的宽度时, 总体结构的透射谱形会呈现为一种Fano线, 这种变化尖锐非对称的Fano线使得结构对于折射率的敏感性高达1 400 nm/RIU。本文还研究了滤波器特性随结构尺寸的变化, 发现在滤波器几何结构一定的情况下, 透射只发生在特定的波长处。该滤波器可以用于光子回路和灵敏探测。

The coupled-resonator structure consisting of a T-shaped resonator and a nanodisk resonator was proposed and numerically investigated by using a two-dimensional finite element method. When the two cavities are at the condition of detuning, the plasmon-induced transparency (PIT) and the sharp asymmetric Fano lines will appear due to the difference of the cavities’transmittance. Fano-lines increase the sensitivity to 1.4×103 nm/RIU. The properties of the structure with different radii of the nanodisk and the length of the rectangle cavity were also analyzed. It is found that the PIT only happens when the staggered system is at around of a fixed location with different geometric construction. This model may be important for photonic-integrated circuits and the sensitivity in sensors.