An optoelectronic device and method of making the same. The device comprising: a substrate; an epitaxial crystalline cladding layer, on top of the substrate; and an optically active region, above the epitaxial crystalline cladding layer; wherein the epitaxial crystalline cladding layer has a refractive index which is less than a refractive index of the optically active region, such that the optical power of the optoelectronic device is confined to the optically active region.