An optical module includes: a circuit board with a recess; a laser box disposed in the recess and electrically connected to the circuit board; a fiber ribbon, wherein one end of the fiber ribbon is connected to the laser box; and a silicon photonic chip electrically connected to the circuit board and to the other end of the fiber ribbon. The laser box includes: a flat base disposed in the recess, with one end of the flat base being coupled to the fiber ribbon; a conductive substrate disposed at the other end of the flat base and electrically connected to the circuit board; a laser chip attached on the conductive substrate; and an upper cover including a top plate and side plates, so that the upper cover caps/is covered on the flat base. A fitting between the flat base and the upper cover facilitates assembly of the conductive substrate and the laser chip in the laser box.