Are optical splitters classified into primary and secondary stages

Optical splitters in PON networks are often deployed in two stages: primary and secondary, to efficiently distribute signals to multiple end users.

Overview of Primary and Secondary Splitting

In Passive Optical Networks (PONs), a single optical signal from the Optical Line Terminal (OLT) is divided to serve multiple Optical Network Terminals (ONTs) at users' premises. To manage large numbers of subscribers while minimizing fiber usage, splitters are deployed in two stages:

• Primary Splitter: The first stage, usually installed in a distribution cabinet, divides the optical signal into several outputs. Typical split ratios for primary splitters are 1:4 or 1:8, depending on the number of households served and network design requirements . The primary splitter determines the initial distribution of optical power and fiber allocation toward secondary splitters.
• Secondary Splitter: The second stage, often located in fiber distribution boxes closer to end users, further divides the signal from the primary splitter. This stage allows finer distribution to individual homes or small groups of users. The secondary splitter typically uses smaller split ratios, such as 1:2 or 1:4, to ensure adequate signal strength at each ONT .

Benefits of Two-Stage Splitting

• Reduced Fiber Count: By cascading splitters, a single OLT port can serve many users without requiring a dedicated fiber for each home .
• Cost Efficiency: Two-stage splitting lowers infrastructure costs by reducing the number of fibers and central office equipment needed .
• Scalability: Networks can be expanded by adding secondary splitters without major changes to the primary distribution .
• Flexibility in Deployment: Primary splitters handle bulk distribution, while secondary splitters allow localized adjustments for new subscribers or network reconfiguration .

Typical Deployment Scenario

For example, in a residential community:

• A primary splitter in the distribution cabinet may serve 12 households with a 1:4 split.
• Each output from the primary splitter connects to a secondary splitter in a fiber distribution box, which further splits the signal to individual homes.
• This hierarchical approach ensures that optical power is efficiently distributed and that the total split ratio does not exceed the PON equipment's optical power limits, often capped at 1:64 .

Conclusion

Yes, optical splitters are commonly divided into primary and secondary stages in PON networks. This two-stage architecture optimizes fiber usage, reduces costs, and allows scalable deployment while maintaining sufficient signal strength for all end users .