Topology optimization of soft matter diffraction gratings

Topology optimization was used to design various optical and photonic solid-state devices. The designs of those devices are commonly composed of only two materials with different refractive indexes, which means that the refractive index is not continuously spatially varying. With additive manufacturing, photoalignment and similar techniques it is possible to make almost arbitrary designs of soft-matter photonic devices. The advantage of such devices over solid-state devices is that the refractive index can continuously change, which can improve performance, and soft-matter devices can be more cost-effective to manufacture. We use topology optimization in combination with a FDTD solver to design soft-matter diffraction gratings for linearly polarized light with the first diffraction order at a specific angle. During the optimization process, we consider material and manufacturing constraints, such as structure relaxation and maximum feature sizes due to the elastic energy associated with the designed structure and chosen material. The diffraction gratings are optimized for light in the IR and visible parts of the spectrum. We calculated designs of soft-matter diffraction gratings which can be manufactured using photopatterning or additive manufacturing and diffract light at the designed angle for specific wavelengths. By using topology optimization for soft-matter optical/photonic devices we can improve their quality and, in some cases, create low-cost alternatives to solid-state devices.