The fabrication of complex integrated optical circuits using thin films will require dielectric patterns of high resolution and edge smoothness. This paper describes an electron-beam technique that has been used to form a curved thin-film light guide and a directional coupler, and is applicable to filters and other more complex components.
J. E. Goell, "Electron-Resist Fabrication of Bends and Couplers for Integrated Optical Circuits," Appl. Opt. 12, 729-736 (1973)