1. The heat shrinkable sleeve with steel wire used to reinforce the connection part of the optical cable shall be sleeved in advance;

2. Remove the coating layer, vertically clamp the optical fiber with the covering pliers, quickly peel off the primary and secondary coating layers with a length of 20mm~- 30mm, rub the optical fiber with a cotton ball or lens paper soaked in alcohol, and clean the fiber core to avoid cracks and scratches on the optical fiber surface.

3. Cut the optical fiber and make the end face. In optical fiber splicing, the most critical process is the fabrication of optical fiber end faces. Whether the end face of the optical fiber is perfect or not determines the loss of the optical fiber connection. The optical fiber end face not only needs to be flat, showing a smooth and flat mirror area, free of burrs and defects, and perpendicular to the axis, but also needs to keep the end face clean to avoid dust pollution.

There are three methods for making end faces: the first is the scoring method. A mechanical cutting knife is used, and a diamond knife is used to scribe a notch on the surface perpendicular to the optical fiber, 10 ㎜ from the coating layer, and the optical fiber will naturally fracture at this notch position after gently bouncing. The second is the cutting clamp method, which uses a self-made hand-held simple clamp for cutting operation. The third is ultrasonic electric cutting method. As long as the instruments are excellent and the operation is proper, the results of the three methods are very good.

4. Put the two optical fibers to be connected into the fusion splicer, and the fusion splicer will automatically weld them.

5. The OTDR instrument is used to test and evaluate the connection performance. After meeting the connection index, the reinforcement protection of the connection part is carried out, that is, the heat shrinkable pipe with steel wire is melted.

6. Finally, after all fiber cores are connected, they shall be collected into the receiving panel and retested with OTDR instrument. Those unqualified shall be re collected or re connected until they are qualified. The splicing loss index of single-mode optical fiber is generally 0.08dB. During construction, indicators can be specified according to the actual situation, but they are generally not greater than 0.08dB.

Optical fiber connection loss is caused by imperfect connection points. There are many factors that affect the imperfect connection points, which can be summarized into two categories, namely external and internal causes.

The internal cause refers to the imperfection of the optical fiber itself, which cannot be reduced by improving the splicing process. It includes core diameter mismatch, refractive index distribution mismatch, poor fiber concentricity, and mode field diameter mismatch. Therefore, during the splicing test, the splicing loss value will appear large positive and large negative phenomena. Through multiple connections, the unidirectional value can only be smaller and the average value tends to zero, but the positive and negative phenomena cannot be avoided. The positive and negative phenomena have a certain impact on the optical fiber transmission loss. In the project, the same batch of optical cables shall be selected as far as possible during optical cable distribution, and A and B ends shall be matched one by one as far as possible to reduce the connection loss to a certain extent.

External factors refer to the poor connection process rather than the imperfect optical fiber itself. External factors have strict requirements for successors. The deviation of the core position in the transverse direction, longitudinal direction and the axial angle of the optical fiber, and the pollution of the optical fiber end face are caused by factors such as untimely maintenance and improper operation of the fusion splicer during the splicing process.

Finally, it should be noted that the heat shrinkable tubes should also be clean, clean and dust-free, otherwise, the dust will damage the connection points during hot melting, causing increased loss. When receiving to the receiving tray, try to make a large circle to avoid increasing the loss caused by small circles. The optical fiber shall be fixed in the receiving tray with adhesive tape to avoid springing up and damage in the future.