A semiconductor structure includes an input array, an output array and a waveguide array. The input array is connected to a first slab structure, while the output array is connected to a second slab structure. The waveguide array is optically coupled to the first slab structure and the second slab structure. The waveguide array includes a first connecting part, a second connecting part and a plurality of waveguide channels. The first connecting part is joined with the first slab structure. The second connecting part is joined with the second slab structure, wherein the second connecting part includes a central portion and at least one flank portion, the central portion is connected to and overlapped with the second slab structure, and the at least one flank portion extends over a side surface of the second slab structure. The waveguide channels are joining the first connecting part to the second connecting part.