The operation and skills of fiber optic fusion splicing technology can be mainly divided into five steps: fiber stripping, fiber cutting, fiber melting, fiber sleeve, and fiber winding.
And tools used for fiber fusion: fusion splicer; fiber cleaver; cable stripper; fiber optic stripper; alcohol; dust-free cloth; fiber protection sleeve. Now we describe the operation of each step in detail.
Preparation of the Fiber End Face
Preparing the fiber end face includes stripping, cleaning, and cutting. The necessary condition for fusion splicing is a qualified fiber end face, and its quality directly affects the quality of fusion splicing.
① Use a cable stripper to peel off the outermost plastic layer of the optical cable and the coating layer in the inner layer until the fiber core is exposed. According to experience, it is appropriate to peel the length of the optical cable in the range of 50~100CM and pay attention to the strength of the stripping.
② Insert a fiber protection sleeve into the fiber that needs to be fused. It is mainly used for the bare fiber part of single-core fiber splicing.
Note: Beware of fiber end surface contamination, the fiber protection sleeve should be threaded before fiber stripping. It is strictly forbidden to penetrate after the end face is prepared.
③ Cut off the aramid yarn and strip the outer sheath of the fiber optic with the fiber optic stripper. The fiber optic stripper should be perpendicular to the fiber optic, and the upper part should be inclined inward at a certain angle. Then use the jaws to hold the fiber gently, and push it out along the axis of the fiber with force with your right hand. Also, the stripping length is suitable for 3-5CM.
Bare Fiber Cleaning
Observe whether some debris remains on the bare fiber. If there is any residue, use a cotton ball or a dust-free cloth with a proper amount of alcohol to wipe it.
① Use a “fiber cleaver” to cut the fiber end-face that has been stripped and is ready for splicing. Note that The cutting length should be moderate. Avoid too long, the fiber protection sleeve cannot cover all the bare fibers. In addition, the cutting action should be natural and stable, not heavy or urgent, to avoid the occurrence of bad end faces such as broken fibers, bevels, burrs, and cracks.
Note: The time for cleaning, cutting, and splicing of bare fibers should be closely connected, and the interval should not be too long, especially since the prepared fiber end faces should not be placed in the air. Handle with care when moving to prevent rubbing against other objects. During the splicing, the “V” groove, pressure plate, and blade of the cutter should be cleaned according to the environment, and the end surface should be prevented from being polluted.
② Put the cut fiber on one side of the fiber fusion machine and fix it.
③ Use a fiber optic stripper to strip off the cladding and coating of the single-mode pigtail. After cleaning, cut to a suitable length with a fiber cleaver. Put the cleaved fiber on the other side of the fusion splicer and fix it.
Note: (Do not touch the fiber end face anywhere) The end face should not exceed the electrode rod.
Fiber Splicing Steps
Fiber splicing is the central link of the splicing work, so high-performance fusion splicing machines and scientific operations during the splicing process are very necessary.
① Check whether the fibers at both ends are aligned on the same horizontal line. Then close the windshield and start. Two optical fibers are fused in a “fusion splicer.”
② After the fusion is completed, the loss of the fusion fiber should be observed. If the loss is below 0.03dB, it is considered qualified.
Note: According to the material and type of the fiber optic before the fusion splicing program, set the key parameters such as the optimal pre-melting main melting current and time and the amount of fiber feeding.
During the fusion process, the “V” groove, electrode, objective lens, and fusion room of the fusion machine should be cleaned in time. Observe at any time whether there are bubbles, too thin, too thick, virtual melting, separation, and other bad phenomena in the fusion.
① After opening the cover to remove the fiber optic, move the fiber protection sleeve to cover the fiber splicing point. Ensure the fiber splicing point is in the center of the fiber protection sleeve.
② Place the fiber protection sleeve in the heating zone of the fiber fusion machine, then cover the heater cover. At the same time, the heating indicator light is on, and the fiber protection sleeve starts to be heated. When the heating light goes out, the heating is completed.
Note: When taking out the fiber optic, you can place it in the cooling tray for a while to avoid being scalded by high temperatures.
Arrange the spliced fiber optic on the fiber patch panel with tools such as fiber splicing trays. The scientific fiber coiling method can make the fiber layout reasonable and prevent fiber breakage caused by extrusion.
Winding Fiber Rules
The rule is that after finishing one or several fiber optics in loose tubes, or fiber optics in a branch direction optical cable, the fiber should be reeled once. Advantages: avoiding the confusion of fiber optic, making the layout reasonable, easy to disk, easy to disassemble, and easier to maintain in the future.
The Method of Winding Fiber
① First, the middle and then both sides. That is to say, place the fiber protection sleeve in the fixing groove one by one and then deal with the remaining fibers on both sides. It is beneficial to protect the fiber joints and avoid possible damage caused by the fiber coil. (This method is often used when the space reserved for the fiber optic is small and the fiber optic is not easy to coil and fix.)
② The internal fiber pigtails are routed counterclockwise along the slot of the splice tray, and the external fiber optics are routed clockwise. The excess pigtail reels are on the winding rings on both sides of the fiber splice reel on the fiber patch panel.
Note: According to the length of the remaining optical fiber and the size of the reserved tray space, it will be coiled naturally according to the trend, and do not pull it hard. The bending radius is ten times greater than that of the optical cable and not less than 30mm. Maximize the use of the reserved tray space and effectively reduce the additional loss caused by the winding fiber.
① Glue the adhesive cable tie fixing seat on the appropriate position to fix the redundant fiber optic. Be careful not to tie the cable tie too tightly, and cut off the excess cable tie.
② It is best to tie a cable tie at the entrance of the leading optical cable to avoid affecting the performance due to the shaking of the optical cable. Finally, cut off the excess cable tie.
The Most Common Problems in Fiber Splicing
The most common cause is poor fiber cutting, such as inclined end faces, burrs, or unclean end faces. It is necessary to re-clean the fibers before performing fusion splicing operations; another case is that the discharge electrodes are aging, and the electrode rods need to be replaced.
① Axial misalignment of the fiber core: Clean the V-groove and fiber holder. If it occurs several times in a row, you need to do a “system parameter self-test.”
② The fiber core angle is wrong: Clean the V-groove and fiber holder; re-cut or place the fiber.
③ Bubbles or cracks: re-cut or clean the fiber optic; increase “pre-melting current” or “pre-melting time”; increase “fusion current” or “fusion time.”
Welding is too Thick or too Thin
It is often caused by the position of the fiber and too fast pushes; the shrinkage of the fusion splicing and the thinning of the joint are generally caused by insufficient feed amount and too strong a discharge arc. These types of problems require adjustments to arc discharge parameters and fiber placement.
① Too thick: reduce the “overlapping length”, it is recommended to do the “discharge correction” experiment.
② Too thin: increase the “overlapping length”, it is recommended to do the “discharge correction” experiment; reduce the “welding current.”
③ Thin wire: increase the “welding current.”
④ Fiber optic separation: do the “system parameter self-test” experiment; reduce the “pre-melting current” or reduce the “pre-melting time.”
Large Loss Before and After Heat Shrinkage
The fiber optic is polluted after stripping the protective sheath. Residual pollutants will press the fiber and cause the fiber to deform so that the splicing loss will increase. At this time, the fiber needs to be cleaned and spliced again.
Welds are Easy to Break
There are many reasons for this situation: the quality of the fiber optic itself is not good; the cutting surface of the fiber optic is not smooth, resulting in a poor fusion effect. Therefore, fiber protection sleeves protect the fragile fiber optics when splicing. At the same time, fix the fiber optic with heat-shrinkable clips to avoid breaking.
The Most Common Problems in Winding Fiber
Special Situation in Winding Fiber
① Handling of special conditions, such as individual optical fibers that are too long or too short, can be coiled separately at the end;
② There are special optical devices that can be processed separately. If it is co-coiled with ordinary optical fibers, it should be lightly placed on top of ordinary optical fibers. A buffer pad is added between the two to prevent fiber breakage caused by extrusion, and the tail fiber of the special optical device should not be too long.
Fiber Loss Increases
When fixing, it should be handled carefully to ensure that the fiber optic is above the minimum bending radius. The fiber patch panel should also be placed carefully to avoid being squeezed and bumped.
Quality Assurance of Optical Cable Connection
Strengthen the monitoring of OTDR to ensure the quality of fiber optic fusion. Reduce the additional loss caused by fiber coil and box sealing.
During the entire follow-up work, the OTDR’s four monitoring procedures must be strictly implemented:
① Carry out real-time tracking and monitoring of each core fiber during the fusion splicing process, and check the quality of each splicing point;
② After each winding fiber, carry out a routine inspection on the winding fiber to determine the additional loss caused by the winding;
③ Before closing the fiber patch panel, conduct a unified test on all optical fibers. Find out whether there is any missing test and whether there is any extrusion on the fiber optic and the connector between the fiber optic reserved discs;
④ After closing the fiber patch panel, perform a final inspection on all fiber optics to check whether the sealing box has damaged the optical fibers.
Fiber splicing is meticulous technical work, and it takes a certain amount of patience to do this work better. Hope this article from HOLIGHT can help you improve your build efficiency in your future work, please feel free to contact us for any further questions: email@example.com.