Abstract: A waveguide having alternating regions of different crystallographic orientations, thereby providing quasi-phase-matching for a non-linear frequency conversion, in which two wafers with epitaxial layers thereon are bonded together having different, preferably opposed, crystallographic orientations. One wafer is etched away, and a grating is etched such that one part of the grating has the orientation of one wafer and the other part has the orientation of the other wafer. Thereafter, a waveguide structure is epitaxially deposited upon the differentially oriented template so that the waveguide is differentially oriented in its axial direction. Thereby, quasi-phase-matching non-linear effects can be achieved.