Structural and Optical Properties of Novel Nanoimprinted Photonic Architectures

Abstract

Nanoscale fabrication methods with high resolution and yielding large area patterns have been a prominent research area in recent years due to their crucial role in the implementation of nanosized devices for various applications. Soft nanoimprinting lithography is an easy and scalable fabrication technique that allows seamless integration of photonic nanostructures in many optoelectronic fabrication procedures. In this talk, we focus on the fabrication of photonic architectures using soft nanoimprinting and their exciting optical properties with applications in light harvesting and sensing. The method can be applied to a wide choice of materials. For example, we have built a superabsorber semiconductor metasurface based on Au/Ge extending from the visible to the Ge bandgap in the near infrared range. This enhanced optical absorption stems from the strong interplay between Brewster modes, sustained by the judiciously nanostructured thin semiconductor on metal film, and photonic crystal modes. In this architecture, we demonstrate near-unity absorption which is robust upon angle of incidence variation. A different choice are cellulose-related materials. The fabrication of photonic and plasmonic structures by moulding cellulose into sub-micrometric periodic lattices using soft lithography is an alternative way to achieve structural colour. The biocompatible cellulose membranes exhibit tuneable colours and may be used to boost the photoluminescence of a host organic dye. Furthermore, we show how metal coating these cellulose photonic architectures leads to plasmonic crystals acting as disposable surface enhanced Raman spectroscopy substrates