By SZROLLBALL | 09 June 2025 | 0 Comments
How to choose FTTX fiber optic splitters?
FTTx distribution splitting refers to how optical signals are divided and distributed in a Fiber to the FTTx network using passive optical splitters. Fiber optic splitter is a key design aspect in Passive Optical Networks (PONs) like FTTH (Fiber to the Home), FTTB (Fiber to the Building), and FTTC (Fiber to the Curb).
Purpose of optical splitters
In FTTx, one optical signal from the OLT (Optical Line Terminal) must serve multiple subscribers. Passive splitters divide that signal optically, enabling cost-effective, point-to-multipoint fiber networks without active electronics in the field.
Types of fiber optic splitters in FTTx
1. Centralized Splitting (Single-Level)
•A single splitter (e.g. 1:32 or 1:64) is installed at a central location (like a Fiber Distribution Hub).
• All distribution fibers run directly from the splitter to each subscriber.
Advantages:
• Easier to manage and maintain
• Centralized control
Disadvantages:
• Higher fiber count leaving the hub
• May require longer distribution cables
2. Distributed Splitting (Two-Level or Cascaded)
• Splitting is done in two stages:
• Primary splitter (e.g. 1:4) near the central office
• Secondary splitters (e.g. 1:8) closer to the customer
Example:
1:4 primary splitter → each output goes to a 1:8 secondary splitter
Total split ratio: 1:4 × 1:8 = 1:32
Advantages:
• Reduces fiber count in feeder cables
• More flexible field deployment
Disadvantages:
• Slightly higher optical loss
• More complex maintenance
Splitter Ratios
• Common ratios: 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, 1:128
• The higher the split ratio, the more users per fiber, but the greater the signal loss.
Split Ratio Typical Insertion Loss
1:2 ~3.5 dB
1:4 ~7.2 dB
1:8 ~10.5 dB
1:16 ~13.5 dB
1:32 ~17 dB
1:64 ~20.5 dB
Note: Total optical budget (including fiber loss, connectors, splices, and splitters) must remain within the limits of the OLT and ONT—for GPON, typically around 28 dB.
Where Are Fiber optical Splitters Installed?
• Central Office / Headend
• Fiber Distribution Hubs (FDH)
• Manholes, cabinets, or wall-mounted boxes
• Multi-dwelling units (MDUs) or building basements
Design Tips
• Match split ratio with subscriber density
• Use cascaded splitting for rural or spread-out areas
• Use centralized splitting for dense urban environments
• Always consider optical power budget and future expansion
Choosing the correct fiber optic splitter for an FTTx or other fiber network depends on several factors related to network design, performance, and deployment environment. Here’s a step-by-step guide to help you make the right choice:
1. Determine Your Network Architecture
Decide whether you are using:
Centralized Splitting
• A single splitter (e.g., 1:32 or 1:64) in a central cabinet.
• Best for urban/dense deployments.
Distributed (Cascaded) Splitting
• Two-stage splitting (e.g., 1:4 followed by 1:8).
• Suitable for rural or spread-out areas.
2. Choose the Appropriate Split Ratio
Match the number of end users with your network capacity:
Split Ratio Max Users Served Use Case Approx. Insertion Loss
1:2 2 Point-to-point extension ~3.5 dB
1:4 4 Small buildings or areas ~7.2 dB
1:8 8 MDUs or business parks ~10.5 dB
1:16 16 Neighborhoods ~13.5 dB
1:32 32 Suburban FTTH deployments ~17 dB
1:64 64 Dense urban deployments ~20.5 dB
Note: Higher split ratios increase loss. Your optical power budget (e.g., for GPON ~28 dB, XGS-PON ~31 dB) must support the total loss from fiber, splices, connectors, and splitters.
3. Consider Splitter Type
PLC Splitters (Planar Lightwave Circuit)
• Most common in modern networks
• Uniform signal distribution
• Supports up to 1:128
• Ideal for wide temperature ranges and stable performance
FBT Splitters (Fused Biconical Taper)
• Older technology
• Best for lower split ratios (1:2, 1:4)
• Slightly lower cost, but less uniform signal distribution
Recommendation: Use PLC for most FTTx and data center applications.
4. Select the Packaging Style
Packaging Type Use Case
ABS Box Indoor cabinets, wall boxes, FDHs
Mini Module Limited space, small enclosures
Tray Type Fiber distribution panels and racks
Rack Mount Data centers or ODFs
LGX Module Modular systems, high-density environments
Bare Fiber Fusion splicing inside splice closures
5. Choose Connector and Fiber Type
• Fiber type: Single-mode (G.652.D or G.657.A) for FTTx
• Connector type: LC, SC, or others depending on your equipment
• Polish type: APC (green, angled) or UPC (blue, flat)
APC connectors are preferred in PON to reduce back reflection.
6. Environment and Installation Conditions
• Indoor or Outdoor? Choose splitters with appropriate casing and IP rating.
• Temperature Range? For extreme environments, check -40°C to +85°C specs.
• Mounting style? Wall-mounted, pole-mounted, rack-mounted, etc.
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