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Department of Physics

The Cavendish Laboratory

Colour change by the bending of a photonic crystalThe group carries out research on flexible, polymer-based colloidal-sphere photonic crystals, which are fabricated by self-assembly.

Under strain, the crystal plane spacing changes. This results in a dynamic change in reflectivity and transmission, which can be seen in the picture. The physics behind these colour changes lies in the size of the polymer spheres used in fabrication and the electric field distribution in the close-packed structure. Incorporating different absorbing materials into the structure allows the control of the absorption in the layers, opening up new applications for sensors or novel filter designs.

Stretched films change colourThe unusual structural colour properties of these industrially fabricated nano-materials have led to support from a number of companies and partners including Kodak, Unilever, and Merck. By stretching the films, the colour changes and extruding the nanoparticle components allows unusual structures to form. Our research also explores how nature incorporates similar techniques for biological structural colour.