Differences Between FBT Splitter and PLC Splitter

03/28/2018

In FTTx and PON architectures, optical splitter plays an increasingly significant role to create a variety of point-to-multipoint fiber optic networks. But do you know what is a fiber optic splitter? In fact, a fiber optic splitter is a passive optical device that can split or separate an incident light beam into two or more light beams. Basically, there are two types of fiber splitter classified by their working principle: fused biconical taper splitter (FBT splitter) and planar lightwave circuit splitter (PLC splitter). You may have one question: what's the difference between them and shall we use FBT or PLC splitter?

What Is FBT Splitter?

FBT splitter is based on a traditional technology to weld several fiber together from side of the fiber. Fibers are aligned by heating for a specific location and length. Because the fused fibers are very fragile, they are protected by a glass tube made of epoxy and silica powder. And then a stainless steel tube covers the inner glass tube and is sealed by silicon. As the technology continues developing, the quality of FBT splitter is very good and it can be applied in a cost-effective way.

ADVANTAGES

FBT splitter is made out of materials that are easily available and low-price, so it is cheaper.
Splitter ratios can be customized.

DISADVANTAGES

Restricted to its operating wavelength (850nm, 1310nm and 1550nm) .
The maximum insertion loss will vary depending on the split and increase substantially for those splits over 1:8.
Because an exact equal ratio cannot be ensured, transmission distance can be affected.
High temperature dependent loss (TDL).
Susceptible to failure due to extreme temperatures or improper handling.

What Is PLC Splitter?

PLC splitter is based on planar lightwave circuit technology. It composes of three layers: a substrate, a waveguide, and a lid. The waveguide plays a key role in the splittering process which allows for passing specific percentages of light. So the signal can be split equally. In addition, PLC splitters are available in a variety of split ratios, including 1:4, 1:8, 1:16, 1:32, 1:64, etc. They also have several types, such as bare PLC splitter, blockless PLC splitter, fanout PLC splitter, mini plug-in type PLC splitter, etc. Therefore, if high split counts are needed, small package size and low insertion loss are also required, you are suggested to choose PLC splitter rather than FBT splitter. For more information about PLC splitter, please refer to How Much Do You Know About PLC Splitter?

ADVANTAGES

Suitable for multiple operating wavelengths (1260nm - 1650nm).
Equal splitter ratios for all branches.
Compact configuration; smaller size; small occupation space.
Good stability across all ratios.
High quality; low failure rate.

DISADVANTAGES

Complicated production process.
Costlier than the FBT splitter in the smaller ratios.

FBT vs. PLC Splitter

(1) Operating Wavelength

FBT splitter can only support three wavelengths: 850nm, 1310nm and 1550nm, which makes its inability to works on other wavelengths. While PLC splitter can support wavelength from 1260 to 1650nm. The adjustable rang of wavelength makes PLC splitter suitable for more applications.

(2) Splitting Ratio

Splitting ratio is decided by the inputs and outputs of an optical cable splitter. The maximum split ratio of FBT splitter is up to 1:32, which means one or two inputs can be splitted into an output maximum of 32 fibers at a time. However, the split ratio of PLC splitter is up to 1:64 - one or two inputs with an output maximum of 64 fibers. Besides, FBT splitter is customisable, and the special types are 1:3, 1:7, 1:11, etc. But PLC splitter is non-customisable, and it has only standard version like 1:2, 1:4, 1:8, 1:16, 1:32 and so on.

(3) Assymetric Attenuation Per Branch

The signal processed by FBT splitters cannot be splitted evenly due to lack of management of the signals, so its transmission distance can be affected. However, PLC splitter can support equal splitter ratios for all branches, so it is more stable.

(4) Failure Rate

FBT splitter is typically used for networks requiring the splitter configuration of less than 4 splits. The larger the split, the larger failure rate. When its splitting ratio is larger than 1:8, more errors will occur and cause higher failure rate. Thus, FBT splitter is more restricted to the number of splits in one coupling. But the failure rate of PLC splitter is much smaller.

(5) Temperature Dependent Loss

In certain areas, temperature can be a crucial factor that affects the insertion loss of optical components. FBT splitter can work stable under the temperature of -5 to 75℃. PLC splitter can work at a wider temperature range of -40 to 85 ℃, providing relatively good performance in the areas of extreme climate.

(6) Price

Owing to the complicated manufacturing technology of PLC splitter, its cost is generally higher than the FBT splitter. If your application is simple and short of funds, FBT splitter is definitely a cost-effective solution.

Conclusion

Although the outer appearance and size of FBT and PLC fiber splitter seem rather similar, their internal technologies and specifications differ in various ways. Over the past few years, splitter technology has made a huge step forward in the past few years by introducing PLC splitter. It has proven itself as a higher reliable type of device compared to the traditional FBT splitter.