Colloidal photonic crystals for active laser applications

Abstract

Interest in photonic crystals (PCs) is increasing from both the scientific and technological viewpoints of photonics research because they have intriguing prospects for manipulating the flow of light at will. So far, there have been many reports on a wide variety of methodologies with regard to the fabrication of 3D-PC structures by top-down processing such as lithographic techniques. In this context, colloidal crystals (CCs)—highly ordered 3D architectures of colloidal particles of polymers, silica, and so forth—have received tremendous interest as one of the alternative and facile fabrication techniques of 3D-PCs. The monodispersed microparticles have an intrinsic capability to assemble well-ordered structures on the substrate by bottom-up processing. When a particle diameter in the CCs corresponds to several hundred nanometers of the light wavelength, the photonic bandgaps (PBGs) can be visualized as Bragg reflection colors. This chapter describes an overview of recent developments in fabrication and uses of CC structures of organic and polymer materials for active laser applications. When light-emitting materials are combined in the CCs, the stimulated laser action at PBG band edge(s) or within the PBG wavelength can be generated by optical excitation. Moreover, the optically excited laser action can be controlled by external stimuli due to the self-organization of organic and polymer materials in the CC structures. This chapter highlights not only the research backgrounds of CC structures as PCs, but also the experimental results of their active laser applications. We believe that a wide variety of CC structures will have leading roles in the next generation of photonic devices of organic and polymer materials.