A single PON port on an OLT can connect to multiple ONUs via a passive optical splitter, typically supporting 8 to 64 outputs depending on the split ratio and network design.

How a PON Port Connects to a Splitter

In a Passive Optical Network, the OLT port serves as the source of the optical signal, which is then fed into a passive optical splitter. The splitter divides the signal into multiple outputs, each going to an Optical Network Terminal (ONT) or Optical Network Unit (ONU) at the customer premises . This allows a single fiber from the OLT to serve multiple subscribers, reducing infrastructure costs and simplifying deployment .

Split Ratios and Capacity

The split ratio determines how many ONUs a single PON port can support. Common split ratios include 1:8, 1:16, 1:32, and 1:64, with higher ratios reducing the optical power per output but increasing the number of users served . For example, a 1:32 split means one PON port can serve 32 ONUs, while a 1:64 split serves 64 ONUs. EPON typically supports up to 1:64, and GPON can theoretically support up to 1:128, though practical deployments often use 1:32 or 1:64 to maintain stable bandwidth .

Splitter Types and Deployment

Two main types of splitters are used in PON networks:

• FBT (Fused Biconical Taper) Splitters: Low-cost, suitable for small splits like 1:2 or 1:4.
• PLC (Planar Lightwave Circuit) Splitters: Highly uniform, ideal for larger splits like 1:32 or 1:64, and preferred for scalable FTTH deployments .

Splitters can be deployed in two architectures:

• Centralized Splitting: Splitters are located at a central office or cabinet, allowing flexible assignment of ONUs via jumpers .
• Distributed Splitting: Splitters are placed closer to the end users in closures or pedestals, with fixed connections that are not easily reconfigured .

Practical Considerations

• Bandwidth Sharing: All ONUs connected to a PON port share the available bandwidth. As long as the optical power is sufficient, each ONU can operate normally .
• Power Loss: Each doubling of the split ratio reduces optical power by roughly 3 dB, so network planners must ensure the OLT and ONUs operate within their power budgets .
• Scalability: Adding new subscribers is straightforward if the splitter has available outputs, making PON networks highly scalable .

In summary, connecting a PON port to a splitter allows a single OLT port to efficiently serve multiple ONUs, with the number of users determined by the split ratio, splitter type, and deployment architecture. Proper planning ensures sufficient optical power, bandwidth, and flexibility for future expansion .