Fiber splicing process steps

What are the process steps of fiber splicing

1. Optical fiber connection

(1) Optical fiber connection. The principle to be followed for optical fiber splicing is: when the number of cores is equal, it should be connected with the corresponding colored optical fiber in the bundle tube.

(2) There are three methods of optical fiber connection: fusion splicing, movable connection, and mechanical connection. Welding method is mostly used in the work. The joint loss of this welding method is small, the reflection loss is large, and the reliability is high.

(3) The process and steps of optical fiber connection:

① Strip the optical cable and fix the optical cable in the splice box. Be careful not to damage the bundle tube. The stripping length is about 1m. Wipe off the ointment with toilet paper. Put the optical cable into the splicing box. When fixing the steel wire, it must be pressed tightly so that there is no looseness. Otherwise, it may cause the optical cable to roll and break the core.

② Fiber splitting Pass the optical fiber through the heat shrinkable tube. Separate different bundle tubes and fibers of different colors, and pass them through the heat shrinkable tube. The optical fiber with the coating stripped off is very fragile, and the heat-shrinkable tube can be used to protect the optical fiber fusion splice.

③Turn on the power of the fusion splicer, use the preset program to perform fusion, and remove the dust in the fusion splicer in time during and after use, especially the dust and fiber fragments in the fixture, mirrors and V-shaped grooves.

The optical fibers used by catv include conventional single-mode optical fibers and dispersion-shifted single-mode optical fibers, and the working wavelengths are also 1310nm and 1550nm. Therefore, before fusion splicing, the appropriate splicing procedure should be selected according to the optical fiber and working wavelength used in the system. If there are no special circumstances, the automatic welding program is generally used.

④ Make the fiber end face. The quality of the optical fiber end face will directly affect the splicing quality, so it is necessary to make a qualified end face before welding. Use a special wire stripper to peel off the coating layer, and then wipe the bare fiber several times with alcohol-soaked cleaning cotton, with moderate force, and then use a precision fiber cutter to cut the fiber. For 0.25mm (outer coating) fiber, The cutting length is 8mm-16mm, and for 0.9mm (outer coating) optical fiber, the cutting length can only be 16mm.

⑤ Place the optical fiber. Put the optical fiber in the V-shaped groove of the fusion splicer, carefully press 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 the fusion can be completed automatically.

⑥Remove the optical fiber and heat the heat-shrinkable tube with a heating furnace. Open the windshield, take the fiber out of the fusion splicer, put the heat shrinkable tube in the center of the bare fiber, and heat it in a heating furnace. The heater can use 20mm miniature heat shrink tubing and 40mm and 60mm general heat shrink tubing. It takes 40 seconds for 20mm heat shrink tubing and 85 seconds for 60mm heat shrink tubing.

⑦The disk fiber is fixed. Coil the spliced optical fiber onto the fiber storage tray. When the fiber is coiled, the larger the radius of the coil and the larger the arc, the smaller the loss of the entire line. Therefore, a certain radius must be maintained to avoid unnecessary loss when the laser is transmitted in the fiber core.

⑧Seal and hang. The field connection box must be sealed well to prevent water from entering. After the fusion splice box is flooded with water, due to the long-term immersion of the optical fiber and the optical fiber splicing point in water, the attenuation of some optical fibers may first appear to increase. Slip on stainless steel hooks and hang on hanging wires. So far, the optical fiber fusion splicing is completed.

2. Optical fiber test

The measurement of optical fiber loss is very important, it is directly related to the quality of optical fiber communication, and can detect possible fault points in time.

The optical fiber is erected, and after the fusion is completed, it is the test work. The instrument used is mainly an otdr tester, which can test the position of the optical fiber breakpoint; the entire loss of the optical fiber link; understand the loss distribution along the length of the optical fiber; the connector loss of the optical fiber connection point .

In order to test accurately, the pulse size and width of the otdr tester should be properly selected and set according to the index of the refractive index n value given by the manufacturer. When judging the fault point, if the length of the optical cable is not known in advance, it can be placed in the automatic otdr first to find out the general location of the fault point, and then placed in the advanced otdr.

Choose a smaller pulse size and width, but it should correspond to the length of the optical cable. The blind area is reduced until it coincides with the coordinate line. The smaller the pulse width, the more accurate it is. Of course, when the pulse is too small, the curve shows noise, which should be just right. Then there is the addition of a fiber detection disc, the purpose is to prevent blind spots nearby from being easy to detect.

When judging the breakpoint, if the breakpoint is not at the splice box, open the nearby splice box, connect the otdr tester, test the exact distance between the fault point and the test point, and use the meter mark on the optical cable to easily find the fault point .

When using the meter mark to find faults, there is still a problem with the twisting rate of the pair-twisted optical cable, that is, the length of the optical cable is not equal to the length of the optical fiber. The length of the optical fiber is about 1.005 times the length of the optical cable. Using the above method can be successfully eliminated. Multiple breakpoints and high loss points.

What are the precautions for optical fiber connection

1. Pay attention to the cutting depth when stripping the optical cable

The key to stripping the outer sheath of the optical cable is to master the cutting depth of the sheath cutter, otherwise it is easy to break the fiber. In actual operation, the sheath cutter should be rotated while paying attention to the incision. If you can see the white polyester tape, you should stop feeding and remove the cutter. This step is a proficient process, and it takes many exercises to master the depth of the knife.

2. Fixing of optical cable and stripping of core tube

After the optical cable is stripped, fix the optical cable in the optical cable splice box, strip the core tube, and do all the preparations before the optical fiber fusion.

At this point should pay attention to:

a) The core bundle tube cannot be twisted. Before fixing the optical cable, you must pay attention to the position of the core tube. When the strength member passes through the fixing screw, the underside of the reinforcement must be a filler tube, not a core tube. The core tube must be in the position where the strength member enters the fiber On the same side as the containment tray, it cannot be twisted on the reinforcement.

If the strength member is pressed on the core tube, the core tube will be deformed by force and cause excessive loss, and the optical fiber in the core tube will also break due to long-term stress, leaving hidden dangers to the project.

b) The length of the reinforcement should be appropriate. After the position of the core bundle tube is determined, the optical cable can be fixed. The fixing of the optical cable must prevent the position of the optical fiber from loosening in the splice box, so as to avoid the increase of optical fiber loss or the problem of fiber breakage caused by the movement of the optical cable position.

The fixing of the optical cable is divided into the fixing of the strengthening member and the fixing of the rest of the optical cable. Pay attention to the length of the reinforcement, if it is too long, it will not fit in the joint box; if it is too short, it will not be able to fix the optical cable.

Generally, when cutting the strengthening member, the distance between the splint fixing the optical cable and the screw fixing the strengthening member should be equal to the remaining length. The fixing of the rest of the optical cable is to tighten the splint with screws after the strengthening member is fixed, and fix it tightly at the optical cable inlet of the splice box.

c) The stripping length of the core bundle tube should be appropriate. After the optical cable is fixed, the core bundle tube can be stripped. If the stripping length is too long, it will reach the groove of the optical fiber heat shrinkable tube, and the remaining fiber will be damaged when the fiber is coiled; if the stripping length is too short, when the fiber core bundle tube is fixed, the fixing clip will be stuck on the optical fiber, which is easy to damage the optical fiber .

Therefore, it is generally advisable to strip it past the two fixing bayonets. At this length, the core bundle tube will not cause damage to the optical fiber and can be well fixed. However, the clips should not be too tight when fixing, otherwise the optical fiber of the core tube will increase loss due to stress, and the optical fiber will break after a long time, leaving hidden dangers to the project.

3. Fiber splicing

The splicing of optical fiber is directly related to the quality and life of the project, and the key lies in the preparation of the end face of the optical fiber. The end face of the optical fiber is smooth, without burrs or defects. The fusion splicer can accept and confirm it well, and can make joints that meet the engineering requirements. Meet engineering requirements. In the process of making the end face of the optical fiber, first when stripping the coating layer of the optical fiber, the wire stripper should be perpendicular to the axis of the optical fiber to ensure that the wire stripper does not scratch the optical fiber;

When cutting the optical fiber, it is necessary to operate in strict accordance with the regulations. When using the end face cutter, the cutting length must be accurate, the action should be fast, and the force should be dexterous to ensure that the optical fiber is broken rather than broken; when taking the optical fiber, it must be Make sure that the optical fiber does not touch any objects to avoid damage to the end face. The end face produced in this way is smooth and qualified. The fusion splicer is the key equipment for optical fiber fusion, and it is also a highly sophisticated and expensive equipment.

In the process of use, the operation must be strictly in accordance with the regulations, otherwise it may cause heavy losses. Special attention should be paid to the operation procedure of the fusion splicer, and the length setting of the heat shrinkable tube should meet the requirements.

4. Protection of remaining fibers

After the optical fiber is fused, it is necessary to protect the optical fiber with a heat shrinkable tube and to retain the remaining fiber.

Should pay attention to:

a) During the fiber coiling process, the bending radius of the fiber coil should not be too small, generally not less than 4mm. If the bending radius is too small, it is easy to cause excessive refractive loss and increased dispersion. After a long time, fiber breakage may also occur.

b) When coiling the fiber, pay attention to the twisting direction of the optical fiber, which is generally an inverted "8" shape. Be careful not to twist the optical fiber. After coiling, put all the optical fiber under the baffle of the storage tray to avoid damage to the optical fiber during packaging.

5. Sealing of joint box

In actual engineering, the sealing of the optical cable splice box is very important. Because the surface of the optical fiber is prone to micro-cracks after the splice box enters the water, the fiber will break after a long time, and most of the splice boxes are directly buried underground, so the splice box must be well sealed.

The sealing of the splice box is mainly the sealing of the two parts between the optical cable and the splice box, and the upper and lower covers of the splice box. When sealing the optical cable and the splice box, the optical cable sheath at the sealing point should be polished first, and the outer sheath should be polished with gauze perpendicular to the axial direction of the optical cable, so that the optical cable and the sealing tape can be combined more tightly and sealed better. . The sealing between the upper and lower covers of the joint box is mainly to prevent the sealing tape from being evenly in the sealing groove of the joint box, and tighten the screws without leaving any gaps.

The above are the key points of relevant knowledge about optical fiber connection that we have brought to you, and we hope to help you. In fact, the growing maturity of optical fiber transmission technology and the need for multi-functional development of cable TV in the future make more and more cable TV stations use optical fiber to transmit cable TV signals. Optical fiber splicing is an important process with a large amount of engineering and the most complex technical requirements in the optical fiber transmission system, and its quality directly affects the transmission quality and reliability of the optical fiber line.