两端对称缺陷对对称结构光子晶体透射谱的影响

通过传输矩阵法理论,研究两端对称缺陷C对一维光子晶体ACmB(AB)n(BA)nBCmA透射谱的影响,发现:当无缺陷C时,透射谱符合镜像对称结构光子晶体的透射谱特征。当引入缺陷C后,随着缺陷折射率nC的增大,禁带中的透射峰逐渐变宽的同时向高频方向移动。缺陷周期数m及其光学厚度DC对透射谱的影响,在数值上具有明显的奇偶特性,m为奇数或DC为奇数倍时,禁带中心均出现一个较宽的通带,且通带宽度随着m或DC的增大逐渐变窄,而且通带上方的振荡加快,但通带中心所处频率位置不变;m为偶数或DC为偶数倍时,禁带中心均出现一条细窄缺陷模,且缺陷模的宽度随着m或DC的增大缓慢变窄,但其位置不变;两端对称缺陷对对称结构光子晶体透射谱的调制规律,为光子晶体设计窄带、宽带光学滤波器或光开关等提供指导。

Effect of bilateral symmetrical defect on symmetrical photonic crystal transmission spectrum

The transmission matrix method theory is applied to study the effect of bilateral symmetrical defect C on the transmission spectrum of symmetrical photonic crystal ACmB(AB)n(BA)nBCmA. The result shows that when there is no defect C,transmission spectrum shows a characteristic of mirror symmetry photonic crystal. When the defect C is introduced,the transmission peak becomes wider and moves to higher frequency with the increasing of refractive index nC. The effect of defect periodicity m and optical thickness DC on the transmission spectrum obviously has a characteristic of numerical parity;when m is odd numbers or the optical thickness DC is odd times,there is a wide transmission band appearing in gap center;it narrows down with the increasing of m or DC,and the oscillation on it becomes intense but its center keeps in a stable frequency. When m is even numbers or the DC is even times,there is a narrow defect mode appearing in gap center,and it slowly becomes narrower with the increasing of m or DC,but its position stays the same. These properties can provide theoretical basis for design of width or narrow optical filter devices.