共查询到18条相似文献,搜索用时 62 毫秒
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在单线缺陷结构中引入两个附加的相邻介质柱,构成一种新型的光子晶体耦合腔波导结构.通过平面波展开法对波导结构的的慢光特性进行了仿真分析,研究了平移线缺陷上下两侧介质柱,以及改变腔体的长度对器件色散特性和群速度的影响.结果表明:与平移缺陷上下两侧介质柱相比,通过改变腔体的长度,不仅可将光群速度低到0.03c(c为真空下的光速),而且器件的有效波长范围接近20nm.利用时域有限差分法得到波导结构的传输场分布图,研究波长的选取对入射激励光在光子晶体耦合腔波导中传输场的影响,发现结构参量优化后的光子晶体耦合腔波导仍然具有良好的传输特性. 相似文献
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对二维介质柱光子晶体耦合腔波导慢光结构进行了研究,发现随着缺陷腔之间晶格个数增多,群速度减小很快,选用7×7超胞单元时耦合腔波导结构的导模最大群速度νg-max只有光子晶体线缺陷波导的1/251.然后对7×7超胞单元的缺陷腔周围四个介质柱半径进行调整,发现新型结构导模的νg-max进一步减小,最小可达到589×10-4c,约为未调整之前的1/5.最后通过比较发现,当改变缺陷腔上下相邻两个介质柱半径时得到的结构具有更好的慢光特性. 相似文献
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采用大介质柱和椭圆介质柱环绕微腔结构构成光子晶体耦合腔光波导(PC-CROW),在获得慢光的同时,其缓存特性也获得了提高。当普通介质柱半径为0.25a(a为光子晶体晶格常数),环绕微腔圆形大介质柱半径为0.35a时,得到小于2.37×10-4c(c为真空中的光速)的导模群速度,这比均匀介质柱微腔波导的最大群速度减小了一个数量级,存储容量也有所下降;考虑到缓存性能,为了进一步改善PC-CROW的慢光性能和缓存特性,将环绕微腔大介质柱椭圆化,在椭圆长轴为0.42a,短轴为0.20a时,获得导模群速度小于2.3053×10-4c,存储容量达到9.8214 bit,品质因子Q也达到了最大值3575.1。 相似文献
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光子晶体异质结耦合波导光开关 总被引:2,自引:0,他引:2
以二维三角晶格光子晶体为研究对象,在该光子晶体中引入两行平行的单模线缺陷波导,以一行耦合介质柱为间距,通过调节部分耦合介质柱的折射率,构筑了光子晶体异质结耦合波导光开关结构。利用平面波展开法和定向耦合原理计算了在不同入射光频率下,缺陷波导间耦合介质柱的折射率不同时的耦合长度,确定了合适的光子晶体异质结耦合波导光开关的结构参数。利用时域有限差分法研究了该光开关中耦合介质柱的折射率变化及异质结构介质柱的位置分布对光信号输出路径的影响。结果表明,通过改变该结构中耦合介质柱的折射率可以改变光的输出路径,可实现光的开关行为。并且异质结构介质柱位置的随机分布对该光开关的影响不大,有助于光子晶体新型滤波器、定向耦合器、波分复用器以及光开关等光子器件的研究。 相似文献
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矩形孔光子晶体波导慢光特性 总被引:1,自引:0,他引:1
在线缺陷光子晶体波导中,利用矩形孔和椭圆孔分别替代临近线缺陷的第二行和第一、三行圆形孔,构成矩形孔光子晶体波导结构.利用平面波展开法对波导的慢光特性进行仿真分析,研究矩形孔的非对称性对慢光带宽和色散特性的影响.研究表明,在慢光区域平均群折射率变化为±10%的情况下,与圆形孔线缺陷波导相比,得到的导模能更好地限制在禁带中,而且当矩形孔宽度参量小于高度参量时,导模可以得到归一化延迟带宽积更大、带宽更宽、色散更小的慢光.通过对波导中矩形孔参量的优化,得到的慢光归一化延迟带宽积最大为0.402,此时带宽为44.4nm,群速度色散为8.0ps2/mm. 相似文献
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In this paper, the slow light properties of the polyatomic Photonic Crystal (PhC) which has multiple different air holes in each primitive cell are investigated. A slow light waveguide with “U-type” group index-frequency curve, which results in nearly constant group index over large bandwidth, is achieved using this new photonic crystal geometry based on the square lattice. Also, the radius and position of the innermost rows of small air holes have been modified to investigate the feasibility of controlling the dispersion relation by subtle structural modification. Numerical results demonstrate that decreasing the group velocity effectively and meanwhile maintaining a large Normalized Delay-Bandwidth Product (NDBP) can be achieved by only modifying the radius of the innermost rows of small air holes. Shifting the innermost rows of small air holes toward the waveguide core is highly beneficial to enlarge the slow light bandwidth, but it contributes nothing to the promotion of NDBP. Our results provide important theoretical basis for the potential application offered by the polyatomic photonic crystal in future optical networks. 相似文献
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Yong Wan Li-Jun Jiang Sheng Xu Meng-Xue Li Meng-Nan Liu Cheng-Yi Jiang Feng Yuan 《Frontiers of Physics》2018,13(2):134202
Slow light with high group index and wideband is achieved in photonic crystal coupled-resonator optical waveguides (PC-CROWs). According to the eye-shaped scatterers and various microcavities, saddle-like curves between the normalized frequency f and wave number k can be obtained by adjusting the parameters of the scatterers, parameters of the coupling microcavities, and positions of the scatterers. Slow light with decent flat band and group index can then be achieved by optimizing the parameters. Simulations prove that the maximal value of the group index is > 104, and the normalized delay bandwidth product within a new varying range of n g > 102 or n g > 103 can be a new and effective criterion of evaluation for the slow light in PC-CROWs. 相似文献
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Lü ShuYuan ZHAO JianLin & ZHANG Dong Institute of Optical Information Science Technology Shanxi Key Laboratory of Optical Information Technology School of Science Northwestern Polytechnical University Xi’an China 《中国科学:物理学 力学 天文学(英文版)》2010,(3)
The slow light propagation in a line waveguide in the two-dimensional triangular photonic crystal has been numerically studied, based on which a wideband photonic crystal waveguide with low group-velocity and low dispersion is proposed. The numerical simulation analysis shows that it is possible to maximize the group index and minimize the group-velocity dispersion in wide bandwidth by increasing the radius of the basic air hole and changing the position of the first two rows of air holes in photonic crysta... 相似文献
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The behaviour of an array of photonic crystal waveguides is numerically investigated. It is shown that high dispersion may
be achieved in the telecommunication window around 1550 nm, with a device whose dimensions are in the order of half a mm2. 相似文献
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A two-dimensional photonic crystal coupled-cavity waveguide is designed and optimized, the transmission spectrum is calculated by using the finite-difference time-domain method, and the group velocity of c/1856 is obtained. To our knowledge, this value of group velocity is the lowest group velocity in a photonic crystal waveguide calculated from its transmission spectrum so far. The result is confirmed by the photonic band structure calculated by using the plane wave expansion method, and it is found that the photonic crystal waveguide modes in a photonic band structure are in accordance with those in the transmission spectrum by using the finite-difference time-domain method. The mechanism of slow light in the coupled-cavity waveguide of photonic crystal is analysed. 相似文献