The present invention provides a process for producing an optical waveguide (20) more particularly for integrated photonic systems. This process comprises provision of polymerizable material; local polymerization of the polymerizable material to produce a multiplicity of polymerized structural elements (14); removal of the unpolymerized regions of the polymerizable material; and heating of the polymerized material more particularly above the glass transition temperature thereof in order to fuse the multiplicity of polymerized structural elements (14) together to form the optical waveguide (20).