An optical splitter has one or more input ports and multiple output ports that distribute optical signals from an OLT to multiple ONTs in a PON network.

Function of Ports

Optical splitters are passive devices that divide a single optical signal into multiple outputs without requiring power. The input port receives the optical signal from the Optical Line Terminal (OLT), while the output ports deliver the signal to multiple Optical Network Terminals (ONTs) or endpoints . In bidirectional PON systems, the same fiber can carry downstream and upstream signals using different wavelengths, allowing the splitter to handle signals in both directions .

Split Ratios and Port Counts

The number of output ports is determined by the split ratio, which defines how the optical power is divided. Common split ratios include 1x2, 1x4, 1x8, 1x16, 1x32, and 1x64, with each output port receiving a fraction of the input power . For example, a 1x8 splitter distributes the input signal equally to eight output ports, each receiving 1/8th of the total power. Some splitters use unbalanced outputs to adjust power along the network path .

Types of Splitters and Port Configurations

• PLC (Planar Lightwave Circuit) splitters: Provide uniform power distribution, ideal for high port counts like 1x32 or 1x64 .
• FBT (Fused Biconical Taper) splitters: Cost-effective for small splits like 1x2 or 1x4, often used in test environments or low-density deployments . Splitters can be deployed in centralized or distributed architectures. Centralized splitters are located in a central office or cabinet, allowing flexible port assignments via jumpers, while distributed splitters are placed in closures or pedestals closer to end users, with fixed port assignments .

Connectors and Network Integration

Splitter ports typically use SC/APC connectors for PON networks, though LC/UPC or SC/UPC may also be used . Each output port connects to an ONT or a local distribution point, enabling scalable network expansion without adding additional OLT ports. In Passive Optical LANs, a single OLT port can serve up to 32 ONTs through a splitter, with downstream signals split and upstream signals combined on the same fiber .

Key Considerations

• Insertion loss: Each output port experiences some signal loss, which must be accounted for in the network power budget .
• Port labeling: Proper labeling ensures correct connections and simplifies maintenance .
• Scalability: Splitter ports allow ISPs to add subscribers by connecting new ONTs to available outputs without major network changes . In summary, the network ports on an optical splitter serve as the interface points for distributing optical signals from a single OLT input to multiple ONTs, with the number of ports, split ratio, and deployment architecture determining network efficiency, scalability, and signal quality .