Fabrication of all-polymer freestanding waveguides

Optical waveguides are used in a wide range of scientific and technological applications. In this paper we focus on the application of waveguides as biosensors with the specific aim of implementing a novel waveguide design for a sensor with improved sensitivity to sub-micron as well as micron-scale analyte entities. The realization of this goal requires ways of fabricating freely suspended polymer thin films of well-defined thickness and having a nanometer scale deep optical grating in their surface. We demonstrate several easy pathways for making such a waveguide module through the combination of advanced polymer handling methodologies based on soft lithography approaches. The resulting waveguide modules are capable of guiding light coupled into the waveguide through its integrated grating coupler. We believe that the presented fabrication methodologies may be of general utility for microfabrication in polymers and that the improved waveguide structures may also find wider use in integrated optics.