How to branch optical fiber cables

Optical fiber branching can be achieved using optical splitters, separable fiber ribbons, or post-installation branching techniques, each suited for different network requirements.

Optical Splitters (Non-Wavelength Selective Branching)

Optical splitters, also called optical couplers, are passive devices that divide a single optical input into multiple outputs or combine multiple inputs into one output. They are widely used in passive optical networks (PONs). Splitters can be classified as:

• Star branching devices: Balanced devices with multiple output ports, typically more than four, distributing signals evenly.
• Tree branching devices: Devices that distribute a single input among several outputs or vice versa . Manufacturing methods include:
• Fused Biconic Taper (FBT): Bare or etched fibers are fused and stretched to allow evanescent mode coupling along the interaction length.
• Planar Waveguide Devices: Fabricated using photolithography and ion diffusion in substrates like glass, silicon, or polymers, or via chemical vapor deposition (CVD) and flame hydrolysis deposition (FHD), .

Separable Fiber Ribbons for Mid-Span Branching

For mid-span branching, especially in FTTH networks, separable fiber ribbons allow individual fibers to be extracted without wasting the remaining fibers. These ribbons can be designed with 2, 4, or 8 fibers, enabling efficient branching at intermediate points. Special tools are used to separate fibers cleanly and connect them to drop cables, improving fiber utilization and reducing installation complexity .

Post-Installation Branching with Plastic Optical Fibers

A post branching method allows branching at any non-terminal position of an existing optical fiber cable. This is particularly useful for plastic optical fibers (POFs), which can tolerate high extensional strain and are easy to cut. The method involves:

• Cutting the desired fiber without disturbing the entire cable.
• Forming a terminal at the branching point.
• Using splices or closures to connect the branched fiber to a new path .

Considerations for Branching

• Fiber type: Single-mode or multimode fibers, or plastic optical fibers, influence the branching method.
• Network design: Star or tree topologies determine whether splitters or mid-span branching is more appropriate.
• Efficiency: Separable ribbons and post-installation branching improve fiber utilization compared to conventional methods where unused fibers are wasted.
• Tools and closures: Proper splicing tools, optical closures, and protective housings are essential for reliable branching . By selecting the appropriate branching method, network designers can optimize signal distribution, installation efficiency, and scalability for optical fiber networks.