Abstract: A photonic integrated circuit structure includes a substrate, a waveguide structure and a spot size converter. The waveguide structure is disposed over a surface of the substrate and has a receiving end. The spot size converter includes a concave mirror and a curved mirror. The concave mirror and the curved mirror are opposite to each other and have a common focus. The concave mirror is arranged to reflect a parallel beam from a transmitting end such that a first reflected beam is able to converge at the common focus, and the curved mirror is arranged to reflect the first reflected beam such that a second reflected beam is directed parallel to the receiving end of the waveguide structure.

Abstract: A photonic integrated circuit structure includes a substrate, a waveguide structure and a spot size converter. The waveguide structure is disposed over a surface of the substrate and has a receiving end. The spot size converter includes a concave mirror and a curved mirror. The concave mirror and the curved mirror are opposite to each other and have a common focus. The concave mirror is arranged to reflect a parallel beam from a transmitting end such that a first reflected beam is able to converge at the common focus, and the curved mirror is arranged to reflect the first reflected beam such that a second reflected beam is directed parallel to the receiving end of the waveguide structure.