Optical modules operate at the physical layer, which is the bottom layer of the OSI model. Its function is quite simple: it achieves photoelectric conversion. Operating at the physical layer of the OSI model, optical modules are core devices in optical. That is, metal medium communication represented by coaxial cables and network cables is gradually being replaced by optical fiber media. They are used in fiber optic communication systems to transmit data over long distances with minimal loss and interference. These modules typically consist of a laser or LED transmitter, a. TOSA: Its main function is to convert electrical signals to optical signals, including lasers, MPD, TEC, isolator, Mux, coupling lenses and other devices, including TO-CAN, Gold-BOX, COC (chip on chip), COB ( chip on board) and other packaging forms.