含梯度折射率缺陷的一维光子晶体滤波性能研究

为实现一维光子晶体更优越的滤波特性，引入渐变折射率缺陷层，可以抑制某些特定频率的电磁波，产生光子禁带。利用时域有限差分（FDTD）法，严格求解麦克斯韦方程组。研究了缺陷层的折射率变化为抛物线型时对应的透射率谱线，并分析了周期介质层的折射率比、厚度比及周期数，对滤波性能的影响。研究表明，增加折射率比，含梯度折射率缺陷层的一维光子晶体可以实现更大的滤波带宽；改变厚度比，可以影响透射峰位置；改变周期数，则可以影响透射率。这一研究结果对提高光子晶体滤波器性能具有一定参考价值。

Filtering characteristics of one-dimensional photonic crystal with gradient refractive index defects

To achieve the superior filtering characteristics of one-dimensional photonic crystal, the gradient refractive index of defect layer is introduced to inhibit certain frequency of electromagnetic wave and get the photonic band gap. Maxwell's equations were solved strictly with the finite difference time domain (FDTD) method. Discuss the corresponding transmission spectrum when changes in the refractive index of defect layer are parabolic. And analysis the impact of the refractive index ratio, thickness ratio and the cycle number of periodic dielectric layer on the filtering characteristics. Research shows that defect layer with gradient index of the one-dimensional photonic crystal has a wider bandwidth when we increase the refractive index ratio; changing the thickness ratio can affect position of the transmission peak; changing the periodic number, may influence the transmittance. Results of this study have some reference values to improve the performance of photonic crystal filters.