Advances in the fabrication of multiple stopbands photonic crystal microparticles

Abstract

Photonic crystals are a new class of optical materials characterized by a dielectric constant that varies periodically with space and features a photonic bandgap. The materials have wide applications in various fields. Inspired by multicolored organisms in nature, photonic structures with multiple stopbands have attracted extensive scientific interest. Photonic crystals can be fabricated through the self-assembly of building blocks such as block copolymers, liquid crystals, and colloidal particles. Compared to thin-film or bulk photonic crystal materials, photonic crystal microparticles exhibit superior flexibility and are typically fabricated using emulsion droplet templates. Despite recent summaries of the construction of multiple stopband structures, microparticles with more than single stopband have yet to be comprehensively analyzed. In this highlight, we systematically summarized the strategies for constructing multiple stopbands photonic crystal microparticles, with an emphasis on emulsion-based templating methods. For example, microfluidics have emerged as a key method for generating highly uniform emulsion droplets. Additionally, other fabrication techniques, including photolithography, one-pot self-assembly, and micromolding are discussed. Finally, we provide an outlook on future developments and challenges in the field of multiple-stopband photonic crystal microparticles.