%0 Journal Article
%T 3D Photonic Nanostructures via Diffusion-Assisted Direct fs Laser Writing
%A Gabija Bickauskaite
%A Maria Manousidaki
%A Konstantina Terzaki
%A Elmina Kambouraki
%A Ioanna Sakellari
%A Nikos Vasilantonakis
%A David Gray
%A Costas M. Soukoulis
%A Costas Fotakis
%A Maria Vamvakaki
%A Maria Kafesaki
%A Maria Farsari
%A Alexander Pikulin
%A Nikita Bityurin
%J Advances in OptoElectronics
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/927931
%X We present our research into the fabrication of fully three-dimensional metallic nanostructures using diffusion-assisted direct laser writing, a technique which employs quencher diffusion to fabricate structures with resolution beyond the diffraction limit. We have made dielectric 3D nanostructures by multiphoton polymerization using a metal-binding organic-inorganic hybrid material, and we covered them with silver using selective electroless plating. We have used this method to make spirals and woodpiles with 600£¿nm intralayer periodicity. The resulting photonic nanostructures have a smooth metallic surface and exhibit well-defined diffraction spectra, indicating good fabrication quality and internal periodicity. In addition, we have made dielectric woodpile structures decorated with gold nanoparticles. 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. 1. Introduction Direct fs laser writing is a technique that allows the construction of three-dimensional micro-and nanostructures [1]. It is based on the phenomenon of multiphoton absorption and subsequent polymerization; the beam of an ultrafast laser is tightly focused into the volume of a photosensitive material, initiating multiphoton polymerization within the focused beam voxel. By moving the beam three-dimensionally, arbitrary 3D, high-resolution structures can be written. By simply immersing the sample in an appropriate solvent, the unscanned, unpolymerized area can be removed, allowing the 3D structure to reveal. A variety of applications have been proposed including microfluidics [2], micro-optics [3, 4], scaffolds for biomolecules and cells [5¨C7], and photonics and metamaterials [8¨C10]. There has been a lot of research efforts to improve the resolution of DLW technology, which for a long time has been in the range of 100£¿nm. The method which most successfully and substantially has increased the resolution not only of single lines but also of 3D structures is DLW inspired by stimulated-emission-depletion (STED) fluorescence microscopy [11, 12]. In STED-DLW, two laser beams are used; one is used to generate the radicals, and the second beam to deactivate them. Several schemes have been proposed including single-photon (rather than multiphoton) excitation [13], a one-color scheme [14] and multiphoton two-color scheme [15, 16]. Structures with very high resolution and very small intralayer distances have been fabricated using this approach.
%U http://www.hindawi.com/journals/aoe/2012/927931/