An example embodiment may include an optical system for obtaining radiation coupling between two waveguides positioned in a non-coplanar configuration. The optical system may include a first waveguide positioned in a first plane and a second waveguide positioned in a second plane. The first waveguide may be stacked over the second waveguide at a distance adapted to allow evanescent coupling between the first waveguide and the second waveguide. The first waveguide and the second waveguide may be configured such that the coupling is at least partly tolerant to relative translation or rotation of the first waveguide and the second waveguide with respect to each other.