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大多数渐变光子晶体渐变透镜都是以正方晶格或三角晶格排布为基础,并且多选择硅或二氧化硅等高折射率材料,研究的波段多为红外波段。随着可见光通信技术的发展,在可见光波段研究低折射率材料的自聚焦透镜变得很有意义。为了迎合这种需求,提出了Sun-flower型渐变光子晶体自聚焦透镜。首先,通过比较TE和TM两种偏振模式Sun-flower渐变光子晶体朗伯透镜在可见光波段的会聚强度,发现TM型的会聚效果远远优于TE型。然后,以TM型Sun-flower渐变光子晶体为基础设计圆柱形自聚焦平板透镜,通过光场传输的模拟计算给出平板透镜在可见光波段自聚焦的拍长,进一步优化平板透镜会聚光强设计透镜的层数,结果表明在层数为22时效果最佳。最后,讨论了列数的减少对平板透镜的影响,结果表明随着列数的减少光强减弱。这对于制作出高性能会聚效果、短焦距、小体积的光学集成器件有重要的指导意义。
Most graded photonic crystal graded lenses are based on square lattice or triangular lattice arrangement, and many choose high refractive index materials such as silicon or silicon dioxide. Most of the studied bands are infrared bands. With the development of visible light communication technology, it has become very meaningful to study the self-focusing lens of low refractive index material in the visible light band. In order to meet this demand, a Sun-flower graded photonic crystal self-focusing lens is proposed. First, by comparing the convergence intensities of the Sun-flower graded photonic crystal Lambertian lenses in both the TE and TM polarization modes in the visible light band, it is found that the convergence effect of the TM type is far superior to that of the TE type. Then, a cylindrical self-focusing flat lens is designed based on the TM Sun-flower graded photonic crystal. The self-focusing slab length of the flat lens in the visible light band is obtained through the simulation of light field transmission. The number of layers, the results show that the best results when the number of layers 22. Finally, the effect of the decrease of the number of columns on the flat lens is discussed. The result shows that the light intensity decreases as the number of columns decreases. This has important guiding significance for making optical integrated devices with high performance converging effect, short focal length and small volume.