FBT vs. PLC: A Technical Comparison for Passive Optical Components
In the field of passive optical devices, Fused Biconical Taper (FBT) and Planar Lightwave Circuit (PLC) are the two primary technologies for manufacturing couplers and splitters. Understanding their distinct characteristics is essential for selecting the optimal component for your system.
Core Technology & Manufacturing
| Feature | FBT (Fused Biconical Taper) | PLC (Planar Lightwave Circuit) |
|---|---|---|
| Principle | Optical fiber fusion. Fibers are twisted, fused, and tapered, allowing light to couple via the evanescent field. | Integrated photonic circuit. A splitting pattern is lithographically etched onto a silica or silicon chip. |
| Process | Mechanical fusing and tapering. | Semiconductor-like fabrication (deposition, lithography, etching). |
| Form Factor | Relatively larger, especially for higher splits. Uses fiber arrays for packaging. | Very compact chip, independent of split count. |
Key Performance & Application Differences
| Feature | FBT | PLC |
|---|---|---|
| Split Ratio | Customizable (e.g., 90:10, 70:30, 50:50). Ideal for tap monitoring. | Fixed and uniform (e.g., 1×8 yields equal ~12.5% per port). |
| Wavelength | Sensitive. Optimized for specific bands (e.g., 1310nm, 1550nm). Dual-windows possible. | Broadband. Operates uniformly across a wide range (e.g., 1260-1650nm). |
| Uniformity | Moderate. Output power can vary between ports. | Excellent. Very low variation between output ports. |
| Channel Count | Practical for low-channel counts (1×2, 1×4, up to ~1×8). | Highly scalable (1×4, 1×8, 1×16, 1×32, 1×64) in the same chip size. |
| Cost Factor | Lower for low-channel counts and simple ratios. | Lower per-port cost for high-split, high-volume applications. |
| Primary Use Case | Custom splits, monitoring taps, WDM devices, pump combiners. | Uniform signal distribution in PON/FTTH, data centers, CATV. |
Choosing the Right Technology
- Choose FBT when: You need a non-uniform or customized split ratio, are working with a limited number of outputs, or require wavelength-specific coupling.
- Choose PLC when: You need uniform, high-channel-count splitting (1×16 and above), require excellent uniformity and stability across a broad wavelength range, or have space constraints.
A Note on Polarization-Maintaining (PM) Components:
For sensitive applications like fiber optic sensing (gyroscopes) or coherent communications, Polarization-Maintaining (PM) couplers are critical. Feiyi OEO specializes in high-performance PM-FBT couplers, engineered to maintain signal polarization with high extinction ratio stability, ensuring integrity in demanding systems. Standard PLC splitters are generally polarization-insensitive.
About Feiyi OEO
Shenzhen Feiyi Optoelectronic Communication Co., Ltd. is a professional manufacturer with expertise in both FBT and PLC technologies. We provide high-quality standard and custom passive optical components, including a full range of PM devices, to meet diverse application needs in telecommunications and sensing.
Learn more about our capabilities: https://www.feiyi-oeo.com/