二维嵌套光子晶体点缺陷耦合腔波导慢光带宽研究

Research on Bandwidth in the Point Defect Two-dimensional Nested Photonic Crystal Coupled-cavity

在完美光子晶体晶格中嵌套半径较小的光子晶体晶格,在中心处构造点缺陷,构成二维嵌套光子晶体点缺陷耦合腔。通过优化调节点缺陷水平和垂直方向四个介质柱的位置增加带宽。利用平面波展开法进行仿真,结果表明:可以在保证10-3c的慢光前提下,相对带宽达到0.000 51,NDBP(归一化延迟带宽积)均能保持在0.34以上;当垂直方向介质柱位移距离为0.4 a时,NDBP值达到了0.404。与未嵌套二维光子晶体点缺陷耦合腔相比,速度相近时,带宽增加了0.000 17。

A small radius photonic crystal lattice was nested in a perfect photonic crystal lattice,and then an empty cell was set in the center to get the point defect two-dimensional nested photonic crystal coupled-cavity.To increase the bandwidth,the air holes′positions were changed in both horizontal and vertical directions.Plane wave expansion simulations on the slow light properties of the PCWs reveal that：the relative bandwidth can reach 0.000 51 when the group velocity keeps with three orders than the speed of the light.The corresponding normalized delaybandwidth product（NDBP）values are all more than 0.34,especially with 0.404 being the highest value achieved when rod is shifted to 0.4ain the vertical position.Compared with the point defect two-dimensional unnested photonic crystal coupled-cavity,bandwidth increases 0.000 17 with the similar velocity.