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Welding joint experiments for telecommunication fiber optics.


Fiber optics, widely used in communication, is embedded in limited length cables of 4 km.

Because this length is not satisfactory on field conditions where distance from distribution points is longer, the necessity of joining these optic fiber cables in high tech conditions without signal loss is mandatory (Gaftoneanu et al., 2007).

At this moment, three types of fiber optics are on the market: single mode (SM), multi mode (MM) and plastic fiber optic (POF).

Welding joint technology is identical for all three and is presented below.


2.1 Preparing the fibers to be welded:

* Achieving of welds require special operations like align together two optical fibers, then they are welded using an electric arc. Fiber optic cable can have from 1 up to 144 (or even more) glass fibers within (Gaftoneanu et al., 2007). In order to weld these fibers, the cable has to be stripped.

* First the outer layer is removed then silk fibers with anti mice purpose and finally the inner layer in order to have access to the buffers with optic fiber, (fig.1).

* Once the protective layers are removed we can notice that the buffers are covered with a waterproof protective gel. This gel can be removed using benzene based solvents.

* After removing the gel, the buffers are cut with a special clipper in order to do no harm to the fibers (fig.2).

* After the buffers are peeled we will have access to the optic fibers within that buffer. These fibers are protected by a special gel against liquids which may fracture during freezing. This gel is removed using methanol and this operation is called pickling (fig.3).

* During these operations the hands must be protected in order to avoid contact with fiber protective gel. It is very important to pay attention for these two operations (cleaning and pickling) due to the fact that gel presence lead to the impossibility of fiber welding. As well the presence of the protective gel may lead to guillotine knife sliding, the cut is not straight to the axis fiber and the welding will have flaws; after pickling the optic fibers thermo retractable collar is introduced onto one of the fibers to be welded in order to ensure rigidity due to metallic element within its internal structure.

* Using the stripper the fiber optic is peeled by protective enamel and is cut at 90[degrees] angle using special guillotine for that operation (fig.4).

* The stripper and the guillotine are special high quality tools and are essential in preparing fiber optic to be welded considering that the quality of the welding depends of how the fiber was peeled and cut (Gaftoneanu et al., 2008).





2.2 Welding

* In order to weld fiber optic we need the equipment to perform this task. Main parts of this equipment are the two electrodes (2, fig.5) which can reach glass melting temperature and two mini cameras placed at 90[degrees] toward each other so the fibers can "be seen" on two axes (1, fig.5).

* A very important role is played by optic fiber guiding mechanism on both sides of the electrodes (3, fig.5).

* This guiding mechanism helps to align the fibers and to push them toward each other during fusion time in order to realize the joint.

* In fig.6, are presented the steps to be followed by optic fiber while welding: on butterfly guiding mechanism are placed the fibers to be welded paying attention not to exceed electrodes length. After closing the butterflies which lock the fibers within guiding mechanism SET button is pressed in order to start welding process. The equipment starts automatically fiber alignment by receiving data from the mini cameras.

* If various reasons are obstructing fiber alignment the equipment will warn us and the procedure is restarted.

* If the fibers are aligned the electrodes are activated, welding temperature is achieved and guiding elements are slowly pushing fiber ends toward each other in order to realize the joint.

* After welding a signal is introduced on one side of the fiber in order to pass the joint. This signal should not exceed 0, 03 dB. If this value is over passed the procedure is restarted. If the welding is accordingly to quality standards, respectively the damping factor is less than 0, 03 dB the welding is stiffened using thermo retractable collar.

* After placing the welding area at half distance the tube is introduced on the upper part of the equipment where an electric resistance is heating the collar (fig.7) which will adjust on the two fibers ensuring mechanical resistance (Gaftoneanu et al., 2007).





2.3 Assembling

* After welding the buffers together with fibers are placed into the trays.

* These trays are equipped with holes where the collars installed in order to protect them against accidental breaking.

* The fibers are placed on both sides of the trays, the buffers being stiffened with a plastic clip (fig.8).

* The trays can be placed in junction boxes or enclosures (Gaftoneanu et al., 2007).


Fiber optic welded joints is mostly used by communication companies because initial investment is recovered by the number of welding operations.

Nowadays, phone and television companies are using fiber optics because is less expensive than copper wires (Gaftoneanu et al., 2007).

Telecommunication companies use the joining of optical fibers by welding because the initially investment is amortized by the huge number of welds that are made.

In the near future we'll assist to the introduction of fiber optic up to the final user, network cards with fiber optic ports has already appear, TV with optical input even videophones with cable optic input.

This paper follows the achievement of optical fiber joints of high quality for information transmission and combines the look and protection.

The research is limited to welding joints of individual wire optic fibers end will be made welding and joining research of simultaneous wire optic fibers.


Gaftoneanu, V.I.; Trif, T.N. & Rosca, R. (2008). Quality and Flaw Criterium at Welding of Telecommunication Optical Fiber, International Conference on Technology and Quality for Sustained Development, Vol.8, No.1 (October 2008) 405-408, ISSN: 1844-9158

Gaftoneanu, V.; Floricel, D.I. & Trif, I.N. (2007). Joining Fiber Optics -I- Manufacturing Technology, International Conference on Materials Science and Engineering,Vol.3,No.1, (February 2007) pp 330-335, ISSN: 1223-9631

Gaftoneanu, V.; Floricel, D.I. & Trif, I.N. (2007). Joining Fiber Optics -II- Welding Technology, International Conference on Materials Science and Engineering, Vol.3, No.1, (February 2007) 336-341, ISSN: 1223-9631

Gaftoneanu, V. & Trif, I.N. (2007). Conditii tehnice la sudarea fibrei optice (Technical terms in fiber optic welfing), Lucrarile conferintei international ASR,Galati. International conference ASR work, Galati. Ed.Sudura pp 91 - 99, ISBN: 1843-4738, Timisoara, September 2007, Ed. Sudura, Timisoara, Vol. 1 no1

*** (2008), America Fujikura Ltd., Accesed on: 2009-05-27
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Article Details
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Author:Gaftoneanu, Valentin; Trif, Tudor; Rosca, Robert; Tanco, Cornel; Feraru, Lucian; Trif, Nicolae
Publication:Annals of DAAAM & Proceedings
Article Type:Report
Geographic Code:4EUAU
Date:Jan 1, 2009
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