4996.1:
Nanoreplication of diffractive optical devices in Spin-on-Glass (SOG) technology
Abstract
Replication by hot embossing in plastics of Bragg gratings, Fresnel lenses and other optical diffractive surfaces with characteristic features in the nanometer range, is a widely used technique in optical industry today. However, for certain applications, plastic structures present problems, for example in those where optical components are exposed to strong irradiation, giving rise to degradation of the plastic polymer chains, or in applications where temperature of operation is strongly varying, so that incompatibilities between dilatation of plastic structures and glass parts lead to a deterioration of the optical device functioning. Therefore, an attractive option is to develop a replication technology in glassy materials (via the so-called sol gel route). These materials are radiation-hard and have low coefficients of thermal expansion. We aim to use these sol gel Spin-on-Glass (SOG) materials to replicate nanostructured surfaces starting from Si or elastomer moulds. In sol gel technology, basic elements of the glass are dissolved in a liquid polymer matrix and are spun onto the textured surface of the mould. Thermal treatment of the structure leads to both evaporation of the polymer residues and to solidification towards the final glass structure, which at this stage can be demoulded resulting in a ready-to-use optical component.