Important Steps for FOC Splicing - technopediasite-Ultimate Resource For Telecom Technical Support


Tuesday, May 26, 2020

Important Steps for FOC Splicing

Important steps for FOC splicing : The basic purpose of fusion splicing is aligning the FOC (Fiber Optic Cable) and fused them by minimizing the splice loss. The splicing machine mainly take care the extrinsic factors for splice loss. What steps should be taken care of during FOC splicing, today I am going to tell you about it. There are also many readers who start commenting only by looking at the headings, it is necessary to read the complete article to get complete information.

In a long link, Fiber have to be joined end to end because cable manufacturer offers cables in limited lengths, typically 1 to 6Km. For example of 80Km FOC link, we have to splice the Fiber. Splice means jointing two fibers. There are two types of splicing available in the market, (a) Mechanical Splice and (b) Fusion Splice. Now the important parameter is splice loss. To achieve good splicing results , it is essential to know both the proper use of fusion splicer and characteristics of optical fiber.
important steps taken during fiber splicing
Steps of fiber splicing

Kinds of FOC Splicing

There are two technologies are common for FOC splicing, fusions and mechanical . FOC Splicing is a process of connecting fibers to fibers.

1. Mechanical Splicing
2. Fusion Splice

Mechanical Splicing

Mechanical splicing is based on the mechanical alignment of two cleaved fiber and it's allow end to end free flow of light in the FOC. This also applies to terminating the fiber on the connectors. The mechanical splices are used on temporary basis for an emergency  jointing. It is used the technique of aligning two Fiber mechanically by V groove method or Elastic –tube method. The typical splice loss is 0.2dB. It is low cost and easy operation.

Purpose of both method of splicing is to facilitate light coupling between two fiber, an index matching gel is often used. Different methods of FOC termination in mechanical splicing used by the manufacturer.

Mechanical splicing can be angle cleaved or non angle cleaved but the mechanical splicing formed the higher return loss. The insertion loss of a mechanical splice is typically <0.5 dB. Some images of the apparatus used in mechanical splicing are given below.
Tools used for mechanical splicing
Used for Mechanical Splicing

Fusion Splicing

A Fusion splice is to connect one Fiber to another permanently. The fusion splicing equipment aligns, fuses and joints two Fiber with very low splice loss and low back reflection .The typical splice loss for SM fiber is 0.02dB. The basic operation is done on bare Fiber. The fusion splicing machine fuses the Fiber with an electric arc which produces a temperature of about 2000 ° C in the range of melting point of glass.

In the process of fusion splicing required the creation of an electric arc between two electrodes. The two cleaved fibers are brought together in the arc, so that both ends melt together.
Process of fusion splicing
Process of fusion splicing

Splicing to splicing optical losses of the splice can vary. It also depends on splicer how much the expert is in the splicing. Optical losses of splice also depend on the alignment mechanism. Splicing machines with core alignments match up the light-guiding channel of the fiber (8μm core) each other. These machines usually produce splice with losses in this area. <0.05dB.
FOC splicing process by splicing machine
FOC Fusion Splicing

I am not promoting any splicing machine here, so I will not write the name of anyone but usually Fujikura machine is used. Some splicing machine align the cladding (125 μm) of a fiber instead of the cores that transport the light.This is an inexpensive technology, but may increase the occurrence of errors, dimensional tolerance of the cladding larger. Specific insertion loss values for these splice machines are better than 0.1dB.

Principle of Operation of Fusion Splicing

When Fusion Splicing Machine was introduced both the PAS ( Profile Alignment System) and LID (Local Injection and Detection) techniques were started .After several R & D and improvements in the technology, the PAS is more popular and latest technique. The S175 V2000 FURUKAWA Fusion Splicer has an active core alignment mechanism to align the fiber by PAS method.

S175 V2000 splicer is used to splice standard Single Mode Fiber(G652), Standard Multimode  Fiber (G651) and special fibers like Non Zero Dispersion Shifted  Fiber (NZDS, G655 ) of Lucent TW ( True Wave) and Corning LF (Leaf  Fiber) etc.

Causes for FOC Splice Loss

There are two cause for the splice loss it means splice loss depends on two factors-

1. Intrinsic Factors
2. Extrinsic Factors

Intrinsic Factors : There is no use of writing too much detail theory here about the Intrinsic Factors and Extrinsic Factors because many friends want to get more knowledge in less time. Due to intrinsic factors these are the causes of splice loss in FOC -

➤Core Diameter/ MFD Mismatch
➤Cladding Diameter Mismatch
➤Numerical Aperture Mismatch
➤Refractive Index Mismatch
Intrinsic Factors for fiber loss
Factors for fiber loss

Extrinsic Factors : These are the reasons of loss found in FOC due to extrinsic factors.

➤End Separation
➤Angular Misalignment
➤Lateral Displacement
➤Fiber Cleaving Angle
Loss in fiber due to the Extrinsic Factors
Loss in fiber due to Extrinsic Factors 

Steps for Splicing Procedure

1. FIBER PREPARATION ( Stripping, Cleaning and Cleaving)

1. FIBER PREPARATION ( Stripping, Cleaning and Cleaving) : Splice loss is directly affected by the quality of the fiber preparation. For better results make sure the V-grooves are clean and the fiber ends are properly cleaned and cleaved.

1. Slide the splice protection sleeve into either the right or the left fiber.
2. Strip the primary coating from each fiber end to expose approximately 35 mm of bare fiber using a primary coating stripper.
3. Insert the fiber into the Stripper and slide the stripper slightly making angle and give thumb pressure to strip properly.
4. Clean the bare fiber with a lint-free tissue soaked in alcohol.

Cleaning of Fiber : Use pure alcohol and wipe the bare fiber in single direction like below mentioned image.
cleaning and cleaver of FOC
Cleaning and cleaver
Cleaving Fiber : Below steps involve in the cleaving of fiber-

1. Open the lid by pressing lid release lever. Slide blade assembly back (opposite direction of arrow).
2. Place a prepared fiber ( Stripped and Cleaned ) across cleaving area.
3. Close the Lid and slide the sliding blade assembly slowly in direction of arrow until sliding blade assembly stops.
4. Push the lid release lever until it stops.
5. Open the lid and take out fiber from the main body.
6. Remove the waste fibers.


Fiber splicing process
Splicing in process 

As mentioned above in fusion splicing, both fibers keep properly in the splicing machine and press the given button and start the splicing process. We have to keep in mind that the splice loss should be 00 to 0.01 dB, finally it should be less than 0.05 dB. After splice put for heating and  after the heat is over, the machine will alarm you, after which the fiber will have to come out and arrange into the tray.

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