A semiconductor package and a manufacturing method thereof are provided. A die stack in the semiconductor package includes a photonic die and an electronic die stacked on the photonic die by a face-to-face manner. A convex lens is disposed at a back surface of the electronic die, and is formed in an oval shape, such that optical beams can be collimated to have circular beam shape, as passing through the convex lens. In some embodiments, the semiconductor package includes more of the die stacks, and includes an interposer lying below the die stacks. In these embodiments, tilted reflectors are formed in the photonic dies and the interposer, to set up vertical optical paths between the interposer and the photonic dies, and lateral optical paths in the interposer. In this way, optical communication between the photonic dies can be established.