Abstract: An optical waveguide circuit including a nonlinear optical device comprises a metal ground plane (21), a polymer core layer (25) in which optical waves are propagated, and polymer clad layers (22 and 26) on opposite sides of the core layer. The waveguide paths are defined by troughs (23) in one of the clad layers. The nonlinear device is made by electrooptically poling part of the core layer which contains a nonlinear moiety. The clad layers (26 and 22) have a significantly higher conductivity than that of the core layer (25) which improves the efficiency of the electrooptic poling.