Broadband is split using an optical splitter

Optical splitters enable broadband fiber networks to share a single optical signal among multiple users, optimizing cost and scalability in FTTH and PON deployments.

What Optical Splitters Do

An optical splitter is a passive device that divides a single optical signal from an Optical Line Terminal (OLT) into multiple outputs for Optical Network Terminals (ONTs) at subscribers' premises, allowing one fiber to serve many users without active electronics . This reduces the number of fibers, OLT ports, and deployment labor, making broadband networks more cost-efficient .

Types of Splitters

1. Fused Biconical Taper (FBT) Splitters: Low-cost, ideal for small splits like 1:2 or 1:4, commonly used in small buildings or short-distance applications .
2. Planar Lightwave Circuit (PLC) Splitters: Provide uniform power distribution, suitable for large splits like 1:32 or 1:64, preferred in dense urban FTTH networks .
3. On-Chip Splitters: Advanced integrated photonic splitters offer low insertion loss, wideband operation, and customizable split ratios for high-performance or quantum photonics applications .

Split Ratios and Bandwidth

The split ratio defines how many outputs a splitter has and how the input power is distributed. For example, a 1:32 splitter divides one input into 32 outputs, with each output receiving roughly equal power . Higher split ratios reduce per-subscriber bandwidth and increase insertion loss, so network planners must balance distance, bandwidth demand, and cost . Typical theoretical bandwidth per ONT for a 1Gbps OLT port is:

• 1:8 → ~125 Mbps
• 1:16 → ~62.5 Mbps
• 1:32 → ~31.25 Mbps
• 1:64 → ~15.6 Mbps Actual bandwidth is usually 70–80% of theoretical values due to protocol overhead .

Deployment Architectures

1. Centralized Splitting: A single high-ratio splitter (e.g., 1:32 or 1:64) is located near the OLT in a Fiber Distribution Hub (FDH) or Optical Distribution Terminal (ODT). Fibers run directly to each ONT. Advantages include minimal signal loss, easy troubleshooting, and efficient OLT port usage .
2. Distributed or Cascaded Splitting: Splitters are placed in multiple locations along the network, sometimes in series (e.g., 1x4 followed by 1x8 to achieve 1:32). This reduces feeder fiber requirements but may increase insertion loss and complicate maintenance .
3. Unbalanced Splits: Some splitters provide unequal power outputs to compensate for distance or bandwidth needs, useful in rural or asymmetric deployments .

Practical Considerations

• Insertion Loss: Each split reduces optical power; for example, a 1:32 split adds ~15 dB loss, while 1:64 adds ~18 dB .
• Distance: Higher split ratios limit maximum reach due to attenuation (~0.2 dB/km for single-mode fiber at 1550 nm), .
• Scalability: Centralized splitters allow easy addition of subscribers by connecting new ONTs to existing outputs .
• Cost Efficiency: Using splitters reduces the number of OLT ports and fibers, lowering CAPEX, but may require higher-power optics for long distances or high split ratios .

Summary

Optical splitters are essential for broadband fiber networks, enabling cost-effective, scalable, and flexible deployment of FTTH and PON systems. Choosing the right splitter type, ratio, and architecture ensures optimal bandwidth, minimal signal loss, and efficient network expansion . Advanced on-chip splitters further enhance performance for high-speed or specialized applications .