基于等离子体缺陷层的一维可调谐微波光子晶体滤波特性

Tunable filter using plasma defect in one-dimensional microwave photonic crystal

等离子体填充到一维介质-真空微波光子晶体的缺陷层构成一种可调谐单通道滤波器.据等离子体的强色散特性,其等效折射率与电磁波频率及等离子体频率等参数有关,因而可以通过改变等离子参数,使一维微波光子晶体缺陷层的谐振频率发生偏移,实现微波光子晶体的可调谐滤波特性.介质层和等离子体层分别采用了时域有限差分(FDTD)算法及分段线性电流密度卷积时域有限差分(PLJERC-FDTD)算法.数值模拟表明,通过改变等离子体频率可以实现滤波通道在光子禁带内较大带宽范围的移动.

A tunable filter is formed when a plasma defect is introduced in the one-dimensional dielectric-air microwave photonic crystal.Plasma is a dispersive medium and its equivalent refractive index is related to the frequency of the incident electromagnatic wave and the plasma frequency,so it is feasible to shift the syntonic frequency of plasma defect by changing the plasma parameters,which behaves as a tunable filter.In the numerical simulation,the finite-difference time-domain method and the piecewise linear current density recursive convolution finite-difference time-domain method are applied to the dielectric and plasma, respectively. The results show that the filter channel of this microwave photonic crystal can be tuned in a wide band in the photonic band-gap by changing the plasma frequency.