Design of low insertion loss, single-mode polymeric waveguides

1. Field of the Invention The invention provides organic optical waveguide devices which are lithographically formed and employ polymeric materials having low propagation loss. An optical waveguide has a substrate; a polymeric buffer layer on a surface of the substrate; a thin, polymeric undercladding layer on a surface of the buffer layer; a pattern of a light-transmissive, polymeric core on the surface of the undercladding layer; and a polymeric overcladding layer on a top surface of the core and on sidewalls of the core and on a portion of the undercladding layer; the undercladding layer having a thickness of from about 10 percent to about 50 percent a thickness of the core. The core has an index of refraction nwhich is greater than an index of refraction of the overcladding layer nand also greater than an index of refraction of the undercladding layer n; wherein n=n−n, and wherein the difference between nand the index of refraction of the buffer nis at least about 1.5 times n.