Abstract: A multilayer coplanar waveguide having a fine-patterned conductive top cover coated with a photosensitive material for optically controlling the phase shift within the waveguide. The multilayer coplanar waveguide comprises a conductive ground plane, a first dielectric layer formed on the conductive ground plane, a second dielectric layer formed on the first dielectric layer, a conductive signal carrier and a pair of conductive floating ground planes flanking the conductive signal carrier formed on the second dielectric layer, a third dielectric layer formed on the conductive signal carrier, the pair of conductive floating ground planes, and the second dielectric layer, fine-patterned conductive strips formed on the third dielectric layer, and a photosensitive material layer formed on the fine-patterned conductive strips and the third dielectric layer.