Design and application of self-assembled photonic crystals

Abstract

Recently, Photonic crystals based on colloidal spheres self-assembly have received great attentions for their advantages such as material economic, facile fabrication and so on. This kind photonic crystal is also called colloidal crystal (CC) or opal. And the inverted structure (inverse opal) with connected macro-cavities could be acquired by utilizing opal as template. Many jobs focus on the design and application of self-assembly photonic crystals and successfully endow them with special function to meet the requirement of different application. For our group, taking advantage of the coupling between CC film and liquid crystals we constructed tunable photonic crystals with optical response to temperature, electric field and photo-irradiation. Shift of the stop-band, change the intensity of reflection or even reverse the reflection peak at the stop-band have been realized (Fig. 1a–1c). <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1–3]</sup> Further, we designed optically switchable birefringent photonic crystal by controlling the orientation of liquid crystal molecules in stretched polymer inverse opal (Fig. 1d).[4] Because spherical bead is an individual unit and has large observation angles with incidence light perpendicular to surface, we also assembled colloidal spheres to micro-beads by evaporation of the homogeneous colloidal emulsion droplets and applied in biomolecule detection and uniform panel display arrays (Fig. 2). <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[5–7]</sup> Finally, it could be anticipated that self-assembly colloidal crystals would have more and more applications in the fields of nano-materials, optical devices, biology and so on.