3D metallic photonic crystals with optical bandgaps

We present our research into the fabrication of fully three-dimensional metallic nanostructures using Diffusion-Assisted Direct Laser Writing, a technique that employs quencher diffusion for the fabrication of 3D structures with resolution beyond the diffraction limit [1]. The fabrication is done by firstly making dielectric structures inside a hard polymer network containing metal-binding groups, and secondly by selectively covering them with silver using electroless plating [2,3]. We have used this method to make 3D spirals and woodpiles with 600 nm intralayer periodicity (Fig l(a, b)). The resulting photonic nanostructures exhibit well-defined diffraction spectra (Fig 1(c)), indicating good fabrication quality and internal periodicity. Transmission measurements of the woodpile structures and corresponding simulations show the creation of a photonic gap inside the optical part of the spectrum, centered at around 700 nm(Fig 1(d)). Our results show that Diffusion-Assisted Direct Laser Writing and selective electroless plating can be combined to form a viable route for the fabrication of 3D dielectric and metallic photonic nanostructures.