Template‐Directed Solidification of Eutectic Optical Materials

Mesostructured materials can exhibit enhanced light-matter interactions, which can become particularly strong when the characteristic dimensions of the structure are similar to or smaller than the wavelength of light. For controlling visible to near-infrared wavelengths, the small characteristic dimensions of the required structures usually demand fabrication by sophisticated lithographic techniques. However, these fabrication methods are restricted to producing 2D and a limited range of 3D structures. When a large volume of structured material is required, the primary approach is to use self-assembly, and the literature includes many examples of mesostructured optical materials formed via self-assembly. However, self-organized materials almost always contain structural imperfections which limit their performance. Emerging work, however, is showing that by performing self-assembly within a guiding template, the defect density in self-assembled structures can be reduced. Particularly interesting is the possibility that utilizing a template can result in the formation of mesostructures not present in either the template or the native self-organizing material. In this review, particular emphasis is placed on emerging results showing the effect of mesoscale templates on the microstructure of solidifying eutectic materials, with a specific focus on how template-directed solidification may be a powerful approach for fabricating optically active structures, including optical metamaterials.