Standard Optical Fiber Fusion Splice 10 Steps And Operations

September 20, 2021

Fiber optic cable fusion splice is an important process with the largest amount of engineering and the most complex technical requirements in the optical fiber transmission system.

The fiber fusion splice quality directly affects the transmission quality and reliability of the optical communications. Therefore, it is extremely important to carry out effective methods and correct welding steps.

Splice Methods

There are generally 2 methods of fiber fusion splice in actual application, the fusion splicing and mechanical splicing. Because the small splice loss, large reflection loss and high reliability, the welding fusion splicing method is the most practical fusion splice method.


When the number of fiber cores is same, the corresponding color fiber in the same loose tube should be used. When the number of cores is different, splicing the large number of cores first and then the small number of cores in order.

The common structures of fiber optic cable are stranded loose tube, central loose tube and skeleton type. The optical fiber colors are divided into blue, orange, green, brown, gray, white, red, black, yellow, purple, pink, and cyan in order.

A multi-core fiber optic cable puts optical fibers of different colors in the same loose tube to form a group, so there may be several loose tubes in an fiber optic cable. Facing the cross-section of the optical cable, take the red loose tube as the first loose tube of the fiber cable, and then green, white 1, white 2, white 3, etc. clockwise..

Fusion Splice Process

  1. Strip and fix

When fixing the multi loose tube (MLT) layer stranded fiber optic cable, because of the layered management of optical fiber, the loose tubes should be placed in order to avoid twisting.

Passing the optical cable into the splice box, and be sure to press tightly when fixing the steel wire without any looseness. Otherwise, it may cause the optical cable to roll the optical core. Take care not to injure the loose tubes, take about 1 meter of stripping length, and wipe off the ointment.

  1. Heat shrinkable tube

Separate optical fibers of different loose tubes and different colors, and passing them through the heat shrinkable tubes. The fiber optic cable with the coating layer removed is very fragile, using a heat-shrinkable tube can protect the optical fiber connection.

  1. Fusion splice machine

Then turn on the fusion splicer and select the appropriate fusion splicing method. The power supply of the optical fiber fusion splicing machine has two types: DC and AC, which should be switched on and off reasonably according to the type of power supply current.

The fusion splicer should be placed in the fusion splicing environment for at least 15 minutes before each use of the fusion splicer. Set the splicing parameters, pre-discharge time, time and main discharge time, main discharge time, etc. according to the fiber type. If there are no special circumstances, the automatic welding procedure is generally selected. Remove the dust and fiber fragments in the fusion splicer in time during and after fusion splice operation.

  1. Make end face

The quality of the fiber end face will directly affect the splicing quality, so a qualified end face must be made before fiber fusion splicing.

  1. Cleaning

Tear the cotton into small pieces with a flat surface, stick with a little alcohol, clamp the striped fiber, wipe along the axis of the fiber with moderate force. Different parts and layers of the cotton should be used in each time, which can improve the utilization rate of cotton.

  1. Cutting

Clean the cutter and adjust the position of the cutter. The position of the optical fiber cutter must be stable. When cutting the optical fiber, the cutting must be natural, stable, and not with heavy or light force. Avoid bad end faces such as broken fibers, bevels, burrs and cracks.       

  1. Placement

Placing the optical fiber in the V-shaped groove of the optical fiber fusion splicing machine. Carefully press on the fiber clamp and the fiber clamp. Set the position of the optical fiber in the clamp according to the cutting length of the fiber. Close the windshield and press the splicing button. Splicing is automatically completed, and the estimated loss value will be displayed on the display of the optical fiber fusion splicer.

  1. Heating

The next step is removing the optical fiber and heat it with the heating furnace of the fusion splicer. Check whether there is bubble or water droplets, a redo is required otherwise.

  1. Coil and fix

The scientific coiling method can make the optical fiber layout reasonable, small additional loss, and withstand the test of time and harsh environment, also avoid the phenomenon of fiber breakage caused by the backlog.

In coiling, the larger the radius of the coil, the greater the radian, the smaller the optical loss of the entire line. Therefore, a certain radius must be maintained to avoid unnecessary loss when the optical light source is transmitted in the fiber core.

  1. Seal splice closure

The external splicing closure box must be sealed well. If there is water entering splice closure, the optical fiber and the optical fiber fusion splice may be immersed in water for a long time, which may cause the increasing optical fiber attenuation.

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Tony Lau is technical manager and co-founder at HOC. He loves writing about content optical fiber communications, specializes in fiber optic cables, FTTH turnkey solutions, ADSS cable, and ODN networks.

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