FBT Splitter for Equal and Unequal Optical Power Distribution
BWNFiber supplies the FBT splitter (fused biconical taper coupler) in connectorized and unterminated configurations for telecom, CATV, FTTx, monitoring and test projects. Choose 1×2, 1×3 or custom port counts with equal or unequal coupling ratios, single/dual/three-window operation and bare, tube or ABS packaging.
Category Products
FBT Splitter Product Range
Product Selection
Find an FBT Splitter for Your Optical Budget
Start with the published products below, then eliminate models that do not match the port configuration, coupling ratio, working window, optical limits, fiber, connector, package or host enclosure.
Port Configuration1×2, 1×3 or another approved model configuration
Coupling RatioEqual or unequal output assignment and link budget
Working WindowRequired wavelengths, fiber mode and fiber grade
Package and TerminationProtected component, module, connectorized or unterminated
Typical Industry Insertion Loss by Coupling Ratio (1×2)
The table shows typical industry reference maxima per path for a 1×2 fused biconical taper coupler. These are not BWNFiber model acceptance limits. Exact values depend on ratio, wavelength window, connectors and package and are confirmed on the current datasheet and order specification.
| Coupling Ratio | Higher-Share Path IL Max. (dB) | Lower-Share Path IL Max. (dB) | Directivity (dB) | Return Loss (dB) |
|---|---|---|---|---|
| 50:50 | 3.4–3.8 | 3.4–3.8 | ≥55 | ≥50 / ≥55 |
| 40:60 | 2.5–2.8 | 4.5–4.8 | ≥55 | ≥50 / ≥55 |
| 30:70 | 1.9–2.2 | 5.6–6.0 | ≥55 | ≥50 / ≥55 |
| 20:80 | 1.2–1.5 | 7.2–7.6 | ≥55 | ≥50 / ≥55 |
| 10:90 | 0.6–0.9 | 10.5–11.2 | ≥55 | ≥50 / ≥55 |
| 5:95 | 0.4–0.6 | 13.5–14.2 | ≥55 | ≥50 / ≥55 |
| 1:99 | 0.3–0.5 | 20.5–22.5 | ≥55 | ≥50 / ≥55 |
Important: The numbers above are industry-typical reference ranges only. BWNFiber model-specific insertion loss, excess loss, PDL and return-loss limits are confirmed on the datasheet for the exact ordered configuration.
Published BWNFiber Model Examples
| Model | Configuration | Fiber / Connector | Window | Notes |
|---|---|---|---|---|
| FBT-1×2-SM-2.0-Bare-5050 | 1×2 singlemode 50:50 | 2.0 mm, unterminated | Confirm on datasheet | Insertion loss ≤3.4 dB, PDL ≤0.1 dB, directivity ≥55 dB (published) |
| FBT-1×3-SM-0.9-FC/APC-33/33/33 | 1×3 singlemode equal | 0.9 mm, FC/APC | Three-window | Equal 33/33/33 output assignment |
| 1×3 SC/APC SM 3.0 mm | 1×3 singlemode | 3.0 mm, SC/APC, 3 m | Confirm on datasheet | 70:30 or 90:10 unequal options available |
These are verified published examples. Package wording and wavelength descriptions can vary across legacy pages; the exact package and window for each ordered model are confirmed against its current datasheet.
Selection Guide
Compare These Specifications Before Selecting an FBT Coupler
A matching nominal ratio does not confirm path loss, working-window, fiber, connector or package compatibility. Use the fields below to shortlist, then verify the exact model datasheet.
| Port Configuration | State the exact input and output count (1×2, 1×3 or other). Do not use a generic 1×N label when the quotation and test record require a fixed number of paths. |
|---|---|
| Coupling Ratio Definition | Provide the nominal share assigned to every output and confirm the ratio convention. For unequal designs, identify the through and tap paths instead of listing only two percentages. |
| Optical Budget | Calculate acceptable loss for every output path, including splitter, connectors, splices, fiber distance and equipment margin. Equal and unequal paths require different limits. |
| Working Window | State the required wavelength or single-, dual- or three-window design and verify it on the approved model datasheet. |
| Fiber Mode and Grade | Specify singlemode or multimode and the exact fiber grade. Do not apply a fiber option published for one model to the complete FBT range. |
| Fiber Diameter and Length | Define bare fiber, 0.9 mm buffer, 2.0 mm or 3.0 mm cable as applicable, together with input and output lengths and jacket requirements. |
| Connector and Polish | Specify connectorized or unterminated fibers. For connectorized assemblies, state SC, LC, FC, ST or another approved interface, together with UPC or APC and the connector assignment. |
| Package and Host Enclosure | Confirm the physical protection, dimensions, cable exits and available space in the tray, box or closure, and the exact package for the ordered model. |
| Test Data and Documents | Request the current configuration, insertion loss by path, excess loss, PDL, return loss, directivity, working window, temperature limits and packing list. |
Three Common FBT Splitter Ordering Mistakes
- Ordering by ratio percentage alone. A 90:10 label does not tell the supplier which port is the through path or what loss limit applies to each path. Always define through vs tap and the acceptance limit for every output.
- Ignoring the working window. A single-window 1550 nm coupler will not meet a dual- or three-window requirement. State the exact wavelengths required by the network before approving the model.
- Assuming package and fiber options are interchangeable. Bare, 0.9 mm, 2.0 mm and ABS packages have different space and protection implications. Confirm the exact package against the host tray or enclosure drawing.
100% Tested FBT Splitter Assemblies
Every BWNFiber FBT splitter is optically tested before shipment. The complete fused biconical taper assembly is verified for coupling ratio, insertion loss per path, excess loss, PDL, return loss and end-face condition, and the result is recorded against the model and serial trace.
- Coupling ratio and insertion loss for every path
- Excess loss, PDL and directivity limits
- Return loss and connector end-face inspection
- Package, labels, pigtail protection and test record
Certification Evidence on Request
BWNFiber can supply project-specific compliance documentation for the approved FBT splitter model, including Telcordia GR-1209 / GR-1221 alignment, RoHS and relevant environmental or mechanical evidence. Because values and qualifications change with configuration, the exact documents are confirmed against your order specification rather than stated as a blanket category claim.
- Model-specific datasheet and optical acceptance limits
- Dimension and package drawing where required
- Compliance evidence matched to the approved configuration
Selection Decision
FBT Splitter or PLC Splitter: Which Fits Your Network
Both are passive splitters, but they suit different jobs. FBT couplers win on small port counts, unequal ratios and lower piece cost; PLC splitters win on uniform multi-channel division. For the full side-by-side, see our PLC vs FBT splitter guide.
| Factor | Choose an FBT Splitter when… | Choose a PLC Splitter when… |
|---|---|---|
| Port count | 1×2, 1×3 or another small fixed count | 1×4 up to 1×64 / 2×N uniform splitting |
| Coupling ratio | Equal or unequal (70:30–99:1) taps | Near-uniform split across all outputs |
| Cost driver | Lower piece cost at low port counts | Lower cost per port at high channel counts |
| Wavelength windows | Single / dual / three-window by build | Broadband, single-chip window set |
| Typical use | FTTH/PON tap, monitoring, test access, DAS | Central office and FTTx distribution to many subscribers |
Match the FBT Coupler to Every Optical Path
A reliable match starts with the required power on the through and tap paths—not the advertised coupling ratio alone.
- Exact input and output configuration
- Equal or unequal ratio and output assignment (through vs tap)
- Allowable loss for the through and tap paths
- Single-, dual- or three-window requirement
- Singlemode or multimode fiber and exact grade
- Fiber diameter, length, package and host enclosure
- Connector family, UPC or APC, labels and quantity
Inspect the Complete FBT Splitter Configuration
Inspection requirements follow the selected model, approved datasheet and order configuration. Review the coupling result and physical construction together.
- Input, through and tap identification where applicable
- Measured ratio and insertion loss for every path
- Excess loss, PDL, return loss and directivity limits
- Fiber mode, grade, diameter and pigtail length
- Connector polish, end-face condition and dust protection
- Package, labels, quantity, test record and packing
Important: port count, coupling ratio, insertion loss, excess loss, PDL, return loss, directivity, working window, temperature, fiber, connector, package and compliance must be verified for the exact model; they should not be assumed across the category.
FAQ
FBT Splitter Selection Questions
These questions cover the decisions that normally affect coupling ratio, optical budget, working window, fiber, termination and quotation preparation.
What is an FBT splitter?
An FBT splitter (fused biconical taper splitter) is a passive optical component that divides or couples optical power between fiber paths by fusing and tapering two or more fibers. Specify the port configuration, coupling ratio, working window, fiber, connector, package and model-specific optical limits.
How does an FBT splitter work?
FBT technology places fibers together, fuses them under heat and tapers the fused section so a controlled share of light transfers between the fibers. The finished component is approved by its measured ratio and optical limits, not the process description alone.
What is the difference between FBT and PLC splitters?
FBT splitters use fused and tapered fibers and are often specified for small port counts or unequal coupling ratios at lower cost. PLC splitters use a planar lightwave circuit and are commonly used for uniform multi-channel division. Choose from the network architecture, channel count and optical budget, not price or technology name alone. For a detailed side-by-side, see our PLC vs FBT splitter guide.
Can an FBT splitter use equal or unequal ratios?
Yes. FBT configurations support equal ratios such as 50:50 and unequal ratios such as 70:30, 90:10, 95:5 and 99:1. The order must define the ratio convention and identify which output receives each nominal share.
How do I choose an FBT coupling ratio?
Calculate the required optical power for the through path and every tap path. Include the model's insertion-loss limits, connectors, splices, fiber distance and equipment margin. A nominal percentage alone does not prove that both paths meet the approved budget.
What is the difference between 1×2 and 1×3 FBT splitters?
A 1×2 FBT splitter divides one input into two outputs, while a 1×3 model provides three outputs. A three-output order must state whether the outputs are equal or assigned project-specific ratios and must include the loss limit for each path.
What are single-window, dual-window and three-window FBT splitters?
These describe the wavelength windows covered by the approved component: single-window (1310 or 1550 nm), dual-window (1310 & 1550 nm) or three-window (1310, 1490 & 1550 nm). State the required network wavelengths and verify the exact working-window specification on the model datasheet.
Can FBT splitters use singlemode or multimode fiber?
Singlemode is standard for FBT couplers; multimode is offered on selected configurations. State the exact fiber mode, grade and dimensions and request matching test limits for the ordered model.
Should I order a connectorized or unterminated FBT splitter?
Choose connectors when the splitter must plug into an approved adapter interface. Choose unterminated fibers when the installer will splice the component inside a tray, box or closure. Define connector loss, polish, fiber length and field-installation method before ordering.
How do I choose an FBT splitter package?
Match the package to the available tray or enclosure space and the required pigtail protection: bare fiber, 0.9/2.0/3.0 mm loose tube, steel tube, ABS box, LGX cassette or rack-mount. Confirm the exact package for the ordered model.
Which FBT splitter specifications should be verified?
Verify coupling ratio, insertion loss for every path, excess loss, polarization-dependent loss, directivity, return loss, working wavelength, temperature, fiber, connector and package. Connectorized and unterminated configurations may require different acceptance limits.
What insertion loss can I expect from an FBT splitter?
A 1×2 50:50 FBT coupler typically shows insertion loss around 3.3–3.8 dB maximum per path; unequal ratios such as 90:10 or 99:1 place most loss on the low-share tap path. Exact values depend on ratio, wavelength window, connectors and package, and are confirmed on the model datasheet.
What insertion loss does a 90:10 or 99:1 FBT splitter have?
In a 90:10 FBT coupler the 90% through path stays near 0.8 dB while the 10% tap path carries about 11 dB; a 99:1 build places roughly 22 dB on the 1% tap and under 0.5 dB on the through path. Values vary with wavelength, connectors and package and are confirmed on the model datasheet.
Are FBT splitters suitable for PON and FTTH?
Yes for tapping. An FBT splitter for FTTH or PON is commonly used where an unequal branch feeds a local ONU drop or a monitoring point while most power continues along the main fiber. For uniform split to many subscribers, a PLC splitter is the typical choice.
Are BWNFiber FBT splitters tested and certified?
Every FBT splitter assembly is optically tested before shipment, with coupling ratio, insertion loss per path, excess loss, PDL, return loss and end-face inspection recorded. Certification evidence such as Telcordia GR-1209 / GR-1221 or RoHS compliance is provided per the approved model and project specification; confirm the exact documents for your order.
What information is needed for an FBT splitter quotation?
Send the input and output configuration, equal or unequal ratio, working window, singlemode or multimode fiber, fiber grade and diameter, pigtail length, connector and polish, package, optical limits, quantity and schedule. Include a link budget or reference model when available.
Can FBT splitters be customized?
Yes. Ratio (equal or unequal), working window, singlemode or multimode fiber and grade, pigtail diameter and length, connector family and polish, and package are all specified per order. Send a BOM, link budget or reference model to confirm the build.
FBT splitter or PLC splitter: which costs less?
For small port counts and unequal ratios, an FBT coupler is usually the lower-cost part. At high uniform channel counts a PLC splitter gives a lower cost per port. Choose by architecture and channel count, not price alone.
Applications
FBT Splitter Applications Across FTTx, CATV, PON and Test Networks
An FBT splitter is specified wherever one optical path must feed a second path at a fixed, often unequal, ratio. The application decides the coupling ratio, working window, optical budget, package and termination.
FTTH and PON Drop Tapping
An FBT splitter for FTTH or PON feeds a local ONU drop or building entrance from the main distribution fiber using a 90:10 or 95:5 tap, keeping most power on the through path. Verify both the through and tap budgets against the OLT optical link budget.
HFC and RF Overlay Monitoring
In cable and RF-overlay plants, a small 99:1 or 95:5 tap samples the downstream signal for a monitoring receiver without disturbing the payload. Specify the tap share, wavelength window and measurement limits the analyzer requires.
OSP Test Access and Demarcation
Field and NOC teams use a tapped coupler at a demarcation or test access point to insert an OTDR or power meter. Choose the tap ratio and connector plan that protect the live service while enabling non-intrusive test access.
DAS, Small-Cell and Fronthaul
Distributed antenna and small-cell fronthaul use unequal couplers to branch a single feed to nearby remote radio units. Match the ratio, window and package to the cell-site enclosure and fiber routing.
CATV and Optical Signal Distribution
Define the operating window, nominal ratio, path-specific loss and connector plan for the signal-distribution architecture instead of selecting by ratio alone.
Sensing, Lab and Instrumentation
For optical sensing, interferometry or bench test, specify the power assigned to the tap, the remaining through power, wavelength window and measurement limits required by the instrument.
Match Every Coupling Path Before You Order
Need FBT Splitters for an Optical Network Project?
Send BWNFiber your link budget, network diagram, BOM or reference model. We can review the port configuration, coupling ratio, working window, fiber, connectors, package and model-specific optical limits.
Request an FBT Splitter Configuration Review