An optical data link comprises a housing, a circuit board, a semiconductor electrical device, an electrically insulating sealing resin, an optical subassembly, a first heat spreader, and a second heat spreader. The circuit board is provided in the housing. The semiconductor electrical device is provided on the circuit board. The electrically insulating sealing resin covers the semiconductor electrical device. The optical subassembly is supported by the housing. The optical subassembly includes a semiconductor optical device. The semiconductor optical device is connected to the semiconductor electrical device through the circuit board. The first heat spreader is provided between the housing and the semiconductor electrical device and is in contact with the housing. The second heat spreader is provided between the housing and the optical subassembly and is in contact with the housing and the optical subassembly. The second heat spreader is located apart from the first heat spreader.