Fiber splicing and fiber testing

Optical cable splicing connects the end of one optical cable with the beginning of the next optical cable to form the entire operation of a continuous optical cable line. The connection point of optical fiber splicing is called optical fiber splice, which has a great influence on transmission quality and maintenance cost. If the optical fiber splice quality is not high, the loss of one optical fiber joint may be equal to the transmission loss of the 500 m~1000 m optical fiber. Let's take a look at the fusion splicing and optical fiber testing of optical fiber engineering.

fiber optic connection. The principle that should be followed for optical fiber splicing is: when the number of cores is the same, it should be connected with the corresponding color optical fiber in the bundle tube.

There are three methods of optical fiber splicing: fusion splicing, active connection, and mechanical connection. Most of the welding method is used in the project. The joint loss by this welding method is small, the reflection loss is large, and the reliability is high.

The process and steps of optical fiber splicing:

① Strip the optical cable and fix the optical cable into the splice box. Be careful not to injure the bundle tube, take about 1m for the stripping length, wipe the ointment with toilet paper, insert the optical cable into the splice box, and fix the steel wire tightly without loosening. Otherwise, it may cause the fiber optic cable to roll and break the fiber core.

②Split the fiber through the heat shrinkable tube. Separate the fibers of different bundles and colors and pass them through the heat-shrinkable tube. The stripped fiber is very fragile, use heat shrink tubing to protect the fiber splice.

③Turn on the power of the Furukawa S176 fusion splicer, use the preset 42 programs to splicing, and remove the dust in the fusion splicer in time and after use, especially the fixture, dust and fiber fragments in each mirror and V-shaped groove. . The optical fibers used in CATV include conventional single-mode fiber and dispersion-shifted single-mode fiber, and the operating wavelengths are also 1310nm and 1550nm. Therefore, before splicing, an appropriate splicing procedure should be selected according to the optical fiber and working wavelength used by the system. Unless there are special circumstances, the automatic welding procedure is generally used.

④ Make the fiber end face. The quality of the fiber end face will directly affect the quality of the connection, so it is necessary to make a qualified end face before fusion splicing. Use a special wire stripper to strip off the coating layer, then wipe the bare fiber with alcohol-dipped cleaning cotton several times 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. For 0.9mm (outer coating) fiber, the cutting length can only be 16mm.

⑤Place the optical fiber. Put the optical fiber in the V-shaped groove of the fusion splicer, carefully press the optical fiber pressure plate and the optical fiber clamp, set the position of the optical fiber in the pressure plate according to the cutting length of the optical fiber, close the windshield, and the fusion can be automatically completed in 11 seconds.

⑥ Remove the optical fiber and heat the heat shrinkable tube with a heating furnace. Open the draft shield, take the fiber out of the fusion splicer, place the heat shrink tube in the center of the bare fiber, and place it in the heating furnace for heating. The heater can use 20mm micro heat shrink tube and 40mm and 60mm general heat shrink tube, 20mm heat shrink tube takes 40 seconds, 60mm heat shrink tube takes 85 seconds.

⑦Fix the disc. Coil the spliced ​​optical fiber onto the optical fiber receiving tray. When coiling the fiber, the larger the radius of the coil and the larger the radian, the smaller the loss of the entire line. Therefore, a certain radius must be maintained to avoid unnecessary losses when the laser is transmitted in the core.

⑧ Seal and hang. The field connection box must be sealed to prevent water from entering. After the fusion splicing box enters the 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 increase. Put on stainless steel hooks and hang on the hanging wire. At this point, the optical fiber fusion is completed.

The optical fiber is being erected, and the test is done after the fusion is completed. When judging the fault point, if the length of the optical cable is not known in advance, the general location of the fault point can be found first.