Connection between optical splitter and ONU

An optical splitter in a PON network distributes downstream optical signals from the OLT to multiple ONUs and aggregates upstream signals back to the OLT. Role of the Optical SplitterIn a Passive Optical Network (PON), the optical splitter is a passive device that divides a single optical signal from the Optical Line Terminal (OLT) into multiple signals for delivery to several Optical Network Units (ONUs) or Optical Network Terminals (ONTs) at the user premises, and vice versa for upstream traffic. This allows a point-to-multipoint topology, enabling efficient sharing of a single fiber among multiple subscribers without requiring powered equipment in the distribution network.

Connection to ONU

The typical connection sequence is: OLT → Optical Splitter → ONU/ONT. The splitter is positioned in the Optical Distribution Network (ODN), which includes feeder fibers, distribution fibers, and access fibers that connect the central office to end users.

The ON

U receives the optical signal from the splitter, converts it into electrical signals, and forwards it to the subscriber's equipment. Upstream data from the ONU is aggregated by the splitter and sent back to the OLT.

Splitting Ratios and Placement

Optical splitters come in various splitting ratios, such as 1: 2, 1: 4, up to 1: 32, depending on the number of ONUs served and network design requirements. They can be centrally located near the OLT or cascaded in the field to reach multiple users. Splitters are compact and can be installed in cabinets, corridor boxes, or rack-mounted enclosures.

Data Transmission Considerations

Downstream: Data is broadcast from the OLT to all ONUs through the splitter.

Each ON

U extracts the data intended for it based on identifiers like GEM port IDs in GPON. Upstream: ONUs transmit data in bursts using TDMA (Time Division Multiple Access) to avoid collisions, and the splitter aggregates these signals back to the OLT. Reliability: Dual-channel or redundant splitters can enhance network reliability, ensuring continuous service even if one path fails.

Summary

The optical splitter is a key passive component in a PON, enabling multiple ONUs to share a single fiber efficiently. It ensures proper distribution of downstream signals and aggregation of upstream traffic, supporting scalable, cost-effective, and reliable fiber-to-the-home or fiber-to-the-building deployments.