Robust Chirped Photonic Crystals Created by Controlled Colloidal Diffusion

摘要

The spontaneous crystallization of monodisperse or bidis-perse colloidal particles subject to interparticle interactions enables formation of various three-dimensional (3D) photonic crystal structures, which are promising for biosensors, tunable organic lasers, and color pigments for displays. Therefore, colloidal photonic crystals have long been studied, focusing on wide-area production with a low defect density, controlled embedding of active defects, and patterning of colloidal crystals with discrete colors to accomplish their practical uses. As a new class of 3D photonic materials with advanced functionalities, colloidal crystals having continuous changes in the lattice constants have been reported, which can provide useful properties based on continuously varying stop band wavelengths along the gradient. However, lack of practical technologies to produce such materials with high crystal stability and high controllability over the gradient severely limits their applications.