Dispersiveness and thickness dependence of the photonic band gap of silica colloidal crystals

作     者：Y.J.He, H.M.Su, J.W.Diao, Z.C.Wei, S.J.Jiang, H.Z.WangState Key Laboratory of Ultrafast Laser Spectroscopy, Zhongshan University, Guangzhou 510275,ChinaF.Q.Tang Institute of Photographic Chemistry, Chinese Academy of Sciences, Beijing 100101, ChinaP.Dong State Key Laboratory of Heavy Oil, University of Petroleum, Beijing 102200, China 

会议名称：《CCAST“光子晶体”研讨会》

会议日期：2001年

学科分类：08[工学] 0803[工学-光学工程] 

关 键 词：photonic band gap amorphous crystal colloidal crystal transmission spectra 

摘      要：正Experimental results demonstrate that the band gap of colloidal crystal changes with boththe thickness of the crystal and the dispersiveness of the spheres. As the thickness decreasesfrom 1 mm, a red shift of band gap with a maximum proportional to the standard deviation ofspheres appears. Such maximum red shifts of 17 nm, 24 nm, 35 nm and more than 106 nmcorrespond to standard deviations of 3.2%, 3.6%, 4.5%, and 8.4% respectively Theseresults imply that in a thin cell, the spaces between the spheres are broad and bring about theappearance of rigorous face-centered-cubic single crystal, while in a thick cell, the narrowinner spaces can not compensate for the deviation of the spheres and makes the bonds of theface-centered-cubic crystal not the same. Especially when the colloidal crystal is assembled byspheres with a standard deviation of 8.4% in a thick cell, the novel phenomenon of a quasi-complete photonic band gap can be observed, which can be explained as an amorphous crystalin the continuous network model. The quasi-complete photonic band gap results from thedecrease of the symmetry of the lattice in the amorphous colloidal crystal.