A curable composition and a process for using the curable composition within a grating-coupled waveguide (GCW) sensor are disclosed. The composition can be used for facile replication of optical components, specifically those used in a label-independent detection system where operation of the waveguide is dependent on the detailed formation of micro and nano size patterns. The photo or electron beam curable composition has low viscosity (≦500 cPs) and cures to an optically clear material with high glass transition temperature (≦70° C.), low shrinkage on cure, low outgassing, and low extractables.