An optical device is provided including an optically localising region comprising a first region having a first refractive index and an array of sub-regions having a second refractive index, the sub-regions in the array positioned at each of the vertices of the triangles in a pinwheel tiling structure. Light passing through the optical device is localised by multiple scattering events within the localising region. The localising region is isotropic so that transmission in the same in all directions and strong localisation occurs for a relatively broad band of frequencies. This is beneficial in a number of applications. The structure can be easily replicated and that there is always a set minimum spacing between the sub-regions.