Abstract: A method for providing an nonlinear, frequency converting optical QPM waveguide device by growing a first ferroelectric oxide film or layer on a second ferroelectric layer or medium wherein, in first and second embodiments, respectively, the second layer is initially provided with a periodic nonlinear coefficient pattern or a periodic pattern comprising a seed layer. During the growth of the first layer, the periodic pattern formed in the second layer, is replicated, transformed or induced into the first layer resulting in a plurality of substantially rectangular prismatic-shaped domains in the first layer having the periodic nonlinear coefficient pattern status based upon the periodic patterning of the second layer.