Introduce PON network technology in detail.

Passive optical network. PON (passive optical network) means that (optical distribution network) does not contain any electronic devices and electronic power supply, and ODN is all composed of passive devices such as optical splitters, without expensive active electronic equipment. Passive optical network includes an optical line terminal (OLT) installed in a central control station and a plurality of supporting optical network units (ONU) installed in a user's house. Optical distribution network (ODN) between OLT and ONU includes optical fiber and passive optical splitter or coupler.

The structure of PON system is mainly composed of OLT: optical line terminal (OLT) is in the central office, optical distribution network (ODN) includes passive optical devices, optical network unit/optical network terminal (ONU/ONT optical network unit/optical network terminal), but the difference is that ONT is directly located at the user end, and there are other networks between ONU and users, such as Ethernet and element management system (EMS), which usually adopt a point-to-multipoint tree topology.

The outstanding advantage of PON network is that outdoor active equipment is cancelled, and all signal processing functions are completed in switches and equipment in users' homes. Moreover, the initial investment of this access method is small, and most of the funds will be delayed until the user really accesses. Compared with the active fiber access system, the transmission distance is shorter and the coverage is smaller, but the cost is low, there is no need to set up another computer room, and it is easy to maintain. Therefore, this structure can serve home users economically.