Difference between FBT coupler and PLC splitter?? Leave a comment

 

FBT means Fused bi-conical taper and PLC means planar light wave circuit. In practical the application of  both FBT coupler and PLC splitter are same ie to split the fiber optic signal.

How FBT coupler and PLC splitters are made?

In FBT coupler two or more fibers are joined together by melting using fusion technology. G652D category fibers are used to make FBT couplers because it is very suitable for fusion method.

In PLC splitter the main components are fiber arrays and PLC chips. Type of splitting needed and its routes will be predefined in the chip. Fiber arrays are connected to both the ends of PLC chip. Example for a 1x 4 PLC splitter, one end of the PLC chip is connected to fiber array with single fiber  and other end to fiber array with four fibers. Epoxy is used to connect fiber arrays to the PLC chip. G657a1 category fibers are used. G657A1 gives better attraction for bent loss performance.

After this procedures in both FBT coupler and PLC splitters a steel protection tube, epoxy and other protection materials are used to protect the fiber joints. There are different categories depend on this such as bare fiber splitters, steel tuber mini module splitters, abs type packed splitters, LGX box type splitters. They are selected according the place where they are used.

Difference in specification

FBT couplers only passes defined wavelengths. Example in a single window FBT coupler there will be a defined wavelength normally 1310 then it only supports 1310 wavelength.

In dual window they support two wavelengths and in triple window it support three wavelengths. Now mostly available couplers are triple window couplers there wavelengths are 1310,1490,1550. In manufacturing time itself their coupling ratios are defined and its test reports will be attached with the products. So this will be useful in networks which have these three wavelengths.

 In PLC splitter its wavelength is defined in manufacturing but it  support 1270 to 1650 optical spectrum wavelengths. This is the main difference between in terms of wavelength between FBT coupler and PLC splitter.

Next difference is PLC splitters have better splitting accuracy than a FBT coupler. If we need to split in ratio of 50:50 ie ½  then in FBT coupler it can vary to  maximum  48:52 . But in PLC it gives exactly ½ splitter ratio

Splitting loss is less in FBT coupler than a PLC splitter. Example 50:50 FBT coupler loss is 3.2 and in ½ PLC splitter, splitting loss is 3.5.

In terms of reliability and temperature environment ,if the products form a high-quality manufacturer both gives a same result.

For a high power signal, FBT is used and it should be made in particular for high power signal support.

To make manufacturing more simple PLC splitter are made in a ratio of 1*2, 1*4, 1*8, 1*16, 1*32, 1*64 which is in a tree shape.

FBT couplers are available in any ratios. Different ratios of FBT couplers are made for testing equipment like 97:3 , 98:2.

Applications

FBT are used where we need to split most sensitive signals like in control room, or inside testing equipment or testing applications. It is not a standard recommendation to use FBT in networks. Its better to use PLC splitters for splitting in network.

In a Fiber to the home network according to the current standards, for a service which needed triple window ie for cable TV 1550 ,for internet 1310,1490 wavelengths, we can use both FBT couplers and PLC splitters. But if any situation came to use another wavelength it wont pass through FBT coupler. Even if it passes the wavelength it shows loss more than permitted. 

In a standard manner it is good practice to use  PLC splitters in network and FBT couplers in control rooms to manage line signals.

It is possible to manufacture both in 2/2 , 2/8/ 3/2, 3/16 etc. (Note : PLC splitter can only be made in tree like structure)

I summary

If you are keeping a standard, PLC splitters in networks and FBT couplers in Control rooms are the suggested model. Real application of FBT couplers are monitoring systems and testing equipment .Even FBT can be made with high accuracy in any ratio with controlled loss but it will be costly than normal but will be cheap for accuracy in PLC splitter. Both of the products are available with different connectors according to the application.