. . . "An electrooptic waveguide device in accordance with claim 3 wherein each of the side chain polymers in the channel waveguiding medium and the cladding thin films is characterized by a recurring monomeric unit corresponding to the formula: ##STR4## where P' is a polymer main chain unit, S' is a flexible spacer unit having a linear chain length between about 2-20 atoms; M' is a pendant group which e" .