A structure includes an optical interposer attached to a package substrate, wherein the optical interposer includes a silicon waveguide, a first photonic component optically coupled to the silicon waveguide, a second photonic component optically coupled to the silicon waveguide, and an interconnect structure extending over the silicon waveguide, over the first photonic component, and over the second photonic component, wherein the interconnect structure is electrically connected to the first photonic component and to the second photonic component, a first semiconductor device attached to the interconnect structure, wherein the first semiconductor device is electrically connected to the first photonic component through the interconnect structure, and a second semiconductor device attached to the interconnect structure, wherein the second semiconductor device is electrically connected to the second photonic component through the interconnect structure.