Relationship between PON port and optical splitter

A single PON port on an OLT can serve multiple end users by connecting to an optical splitter, which divides the optical signal into multiple outputs for ONTs or ONUs. How a PON Port Connects to an Optical SplitterIn a Passive Optical Network (PON), the PON port on the Optical Line Terminal (OLT) is the active interface that sends and receives optical signals. The optical splitter is a passive device that takes the signal from this PON port and divides it into multiple outputs, allowing one PON port to serve many subscribers simultaneously.

For example, a 1: 32 splitter can distribute the signal from a single PON port to 32 Optical Network Terminals (ONTs) at users' homes.

Split Ratios and Network Capacity

The split ratio of the optical splitter determines how many end users a single PON port can support. Common split ratios include 1: 8, 1: 16, 1: 32, and 1: 64. Choosing the correct split ratio is critical: a higher split ratio increases the number of users per PON port but reduces the optical power per user, which can affect signal quality and bandwidth availability.

Splitter Deployment Architectures

Optical splitters can be deployed in two main architectures: Centralized Splitting: A single-stage splitter is installed near the OLT, directly distributing the signal to all end users. This simplifies management but requires more fiber from the OLT to the splitter. Distributed (Cascaded) Splitting: Multiple splitters are deployed in stages closer to the subscribers.

This reduces fiber usage and improves network survivability but increases field maintenance complexity. Hybrid approaches are also common, combining centralized and distributed splitting to optimize cost, scalability, and performance.

Practical Implications

The relationship between a PON port and an optical splitter is fundamental to network design and scalability. By using splitters, service providers can: Reduce the number of OLT ports required for a given number of subscribers. Minimize fiber deployment costs while maintaining service quality.

Easily add new subscribers by connecting additional ONTs to existing splitter outputs, provided the splitter's capacity is not exceeded. In summary, the PON port provides the optical signal, and the optical splitter distributes it efficiently to multiple users, forming the backbone of cost-effective and scalable FTTH PON networks.