An integrated optoelectronic or optical device is formed by a polarization-splitting grating coupler including two optical waveguides, a common optical coupler and flared optical transitions between the optical coupler and the optical waveguides. The optical coupler is configured for supporting input/output of optical waves. A first region of the optical coupler lies at a distance from the flared optical transitions. The first region includes a first recessed pattern. Second regions of the optical coupler lie between the first region and the flared optical transitions, respectively, in an adjoining relationship. The second regions include a second recessed pattern different from the first recessed pattern.