Abstract: This invention pertains to a device and method for making same. The device includes a substrate supporting optical waveguide, an overlay waveguide and a mode coupler for coupling between the substrate-supported and overlay waveguides. One embodiment includes a high-confinement overlay waveguide capable of low-loss bends with small bend radii, down to tens of microns, which represents two orders of magnitude improvement over prior art. One embodiment includes a feedback path enabled by the high-confinement waveguide, capable of implementing tunable ring resonator filters with free spectral ranges over 100 GHz and modulators with compact and interferometrically stable feedback paths. Another embodiment includes a periodically poled lithium niobate section capable of integrating wavelength conversion within a compact feedback path. Another embodiment includes an amplifier section, which may be incorporated in the feedback path.