Optical splitter inside the optical cable junction box

Optical splitters inside a junction box divide a single incoming fiber signal into multiple outputs, enabling efficient distribution to multiple users without active power.

Function of Optical Splitters

An optical splitter is a passive device that splits an incoming optical signal into two or more output signals or combines multiple inputs into one, without requiring electricity . This allows a single fiber from the central office to serve multiple endpoints, such as homes in a FTTH network, while maintaining signal quality . Splitters are essential in passive optical networks (PONs), including GPON, EPON, and FTTH deployments .

Types of Optical Splitters

1. PLC (Planar Lightwave Circuit) Splitters: Use lithography on a silica substrate to evenly split light with minimal loss, suitable for larger-scale applications and high-density networks . Common splitting ratios include 1:32 or 1:64 .
2. FBT (Fused Biconical Taper) Splitters: Made by fusing and stretching fibers, offering customizable splitting ratios, typically used for smaller-scale or lower-density networks .

Placement Inside Junction Boxes

Optical splitters are often housed in optical cable junction boxes or fiber distribution boxes, which provide mechanical protection, dustproofing, and waterproofing . Placement depends on network design:

• Primary splitters are installed in central offices, main distribution frames, or large optical crossover boxes to distribute signals to multiple secondary locations .
• Secondary splitters are placed in junction boxes closer to end users, such as residential optical crossover boxes or community distribution points, to further split signals for individual households .

Installation Considerations

• Routing: Optical fibers are routed from upstream nodes to the splitter inside the junction box using adapters and optical jumpers .
• Splitting Ratios: Choose ratios based on user density; centralized splitting (e.g., 1:32) is ideal for dense urban areas, while cascaded splitting (e.g., 1:4 followed by 1:8) suits dispersed rural areas .
• Protection: Junction boxes should provide physical security, prevent dust and moisture ingress, and allow easy access for maintenance .
• Flexibility: Splitters can be installed in wall-mounted, pole-mounted, or cabinet-type boxes depending on network layout and environmental conditions .

Summary

Inside an optical cable junction box, splitters efficiently distribute optical signals to multiple users, supporting both centralized and cascaded network designs. Proper selection of splitter type, splitting ratio, and secure installation ensures minimal signal loss, network reliability, and ease of maintenance in FTTH and other PON systems .