A structure including a photonic integrated circuit die, an electric integrated circuit die, a semiconductor dam, and an insulating encapsulant is provided. The photonic integrated circuit die includes an optical input/output portion and a groove located in proximity of the optical input/output portion, wherein the groove is adapted for lateral insertion of at least one optical fiber. The electric integrated circuit die is disposed over and electrically connected to the photonic integrated circuit die. The semiconductor dam is disposed over the photonic integrated circuit die. The insulating encapsulant is disposed over the photonic integrated circuit die and laterally encapsulates the electric integrated circuit die and the semiconductor dam.