PASSIVE OPTICAL NETWORKING (PON/XGS)

In a Passive Optical Network (PON), the network originates at a central office or head end equipped with an Optical Line Terminal (OLT). The OLT transmits data through a single fiber-optic cable to a passive optical beam splitter, which multiplies and distributes the signal across multiple Optical Network Terminals (ONTs). Each ONT connects directly to end-user devices such as computers, telephones, and televisions. Since the splitter broadcasts the same data stream to multiple endpoints, ONTs filter, and process only data meant for their connected devices, secured through encryption.

Optical splitters are passive devices that divide a single fiber-optic signal into multiple outbound fibers. At its simplest, an optical beam splitter uses two back-to-back prisms to split one signal into two separate paths. The PON/XGS standard supports up to 256 splits per port. Split configurations can be centralized, connecting directly from one OLT port to multiple customer ONTs, typically at a ratio of 1:32, or cascaded, where one stage 1 splitter connects to multiple stage 2 splitters, normally achieving a ratio of 1:8 per stage, allowing one OLT port to service up to 64 customer ONTs.

PON/XGS, defined by the ITU-T G.9807.1 standard, provides 10 Gbps symmetric data transmission for passive optical networks. The latest revision in 2023 addresses specifications such as out-of-band noise limits, ensuring enhanced performance and reliability for optical access networks.