What is the Splicing of Optical Fibers & Their Techniques

To overcome the disadvantages of optical fiber connectors, the splicing of optical fibers is used to maintain permanent connections between the two optical fiber cables. The fiber optic cables of various lengths like more than 5kms, 10kms, etc., are not capable of the permanent connection and can’t run for a longer run. And also not suitable for repeated connections and disconnection of cable connections. So, it is necessary to splice the fiber optic cables with two lengths to join the cables together that can provide sufficient permanent connection for a longer run. This article gives a brief description of the splicing of optical fiber cables and types.

What is the Splicing of Optical Fibers?

The splicing of optical fibers is one of the techniques used to join two optical fiber cables for permanent connection. This technique is also known as termination or connecterization. This method is mostly preferred when two types of cables (for example 48-fiber cable and 12-fiber cable) are joined together for a longer run with a single length of fiber cable.

The buried optical fiber can be restored by splicing of optical fiber method. This method is mainly used in optical communication networks for long-distance transmission of signals/data.

Splicing Techniques of Optical Fibers

There are two techniques in splicing of optical fibers depending on the insertion loss, cost, and performance characteristics. They are fusion splicing and mechanical splicing. The mechanical splicing is again divided into two types such as V-grooved splicing and elastic-tube splicing. The two optical fiber cables should be aligned properly while splicing and at the same time its geometrical factors and the mechanical strength should be considered.

Fusion Splicing

This technique of splicing gives the permanent connection between the two optical fiber cables and gives a longer life with less attenuation. The two cores of fiber cables are joined or fused electrically or thermally. That means an electric device or an electrical arc is used to fuse the two fiber optic cables and produces a connection between them. This technique is very costly and works for a longer period.
The schematic diagram of the fusion splicing of optical fiber technology is shown below.

Fusion Splicing of Optical Fibre
Fusion Splicing of Optical Fibre

In this method, the two fiber cables are aligned together by using a device called a fusion splicer. So, those cables can be fused or joined together to form a connection with the help of an electric arc more precisely. The heat produced by the electric arc can give a transparent and continuous non-reflective connection between the two optical fiber cables with less attention, and insertion losses. The light loss will be low in this technique. So, it is most widely used and expensive than mechanical splicing of optical fiber cable.


The functions of the fusion splicer used in the splicing of optical fiber are,

  • It helps to align the optical fibers with more precision
  • It helps to create an electric arc or heat to fuse or join or weld the optical fibers together
  • This method has less attention loss of 0.1dB, and also black reflection loss is low. The insertion losses (<0.1dB) are less in both multimode and single-mode optical fiber splicing.
  • The disadvantage of fusion splicing is, if excess heat is generated to melt the fiber cable for joining, then the join would be delicate and can’t be used for a longer run.

Mechanical Splicing

This technique doesn’t require a fusion splicer to join the optical fiber together. It uses index matching fluid to hold and align the single or more fiber cables assembled in a place to join them together. The mechanical splicing acts as a junction to join the optical cables more precisely.

When the optical fiber cables are joined together to pass the light from one to another, the loss of light will be low if we use the mechanical splicing technique. That means insertion loss, splicing loss will be nearly 0.3dB. But it produces high back reflection when compared to fusion splicing. It is very easy to repair and install for both multimode and single-mode optical fiber cables.

2.1 V-Grooved Splicing

It is one of the types of mechanical splicing, which uses a substrate in a V-shape made up of ceramic, silicon, plastic, or any other metal. The ends of two optical fiber cables are placed in the groove as shown in the figure below.

V-Grooved Splicing
V-Grooved Splicing

When the two ends are placed in the groove in proper alignment, then they are bonded or joined together by using index matching gel and gives a perfect grip to the connection.

In this type, the fiber losses are more because of cladding diameter, core diameter, and position of the core to the center. It doesn’t form a permanent connection. Hence, it is used for Semi-permanent connections.

2.2 Elastic-Tube Splicing

In this type of splicing, an elastic tube is used to form a connection between the two optical fiber cables. It is mainly used for multimode optical fiber cables. The fiber losses are low and almost the same as in the fusion splicing type. It requires less equipment and skillset to install and repair when compared to fusion splicing.

Elastic-Tube Splicing
Elastic-Tube Splicing

The diagram of elastic-tube splicing is shown above. An elastic-tube called rubber with a small hole is used. The diameter of the optical fiber for splicing should be more than the diameter of the hole in the rubber. The two ends of the optical fine cables have tampered with for easy insertion without any loss into the tube.

If the optical fiber is inserted inside the hole, then the asymmetrical force exerted on the fiber cable gives the proper alignment and expansion to form a connection between the fiber cables. The optical fiber cable moves to the tube axis and the diameters of the fiber cable are spliced.

Advantages of Fiber Splicing

The advantages of fiber splicing are,

  • The splicing of optical fiber cable is used for long-distance transmission of optical or light signals.
  • The loss of back reflection is less during the light transmission
  • Gives permanent and Semi-permanent connections between the two optical fiber cables.
  •  This technique can be employed in both single-mode and multimode optical fiber cables.

Disadvantages of Fiber Splicing

The disadvantages of fiber splicing are,

  • The fiber losses will be more during the transmission of light.
  • If the splicing is increased, then the cost of optical transmission or communication system will be more.

Thus, this is all about the splicing of optical fiber cables– types, advantages, and disadvantages of splicing. The purpose of the splicing is to join the two optical fiber cables to form a permanent connection and reduce light loss in transmission. Here is a question for you, “What are the applications of splicing of optical fiber cables.