Optical cable splicing process

What is optical cable splicing and what should be paid attention to when splicing optical cables. The connection point of optical fiber connection is called fiber optic splice, which has a great influence on transmission quality and maintenance cost. If the quality of the fiber connection is not high, the loss of a fiber joint may be equal to the transmission loss of 500 m - 1000 m fiber. Optical fiber splicing requires that the additional loss of the optical fiber connector is small, the connector has high reliability, has good mechanical properties, and maintains long-term stability of characteristics; on-site construction requires simple operation, short splicing time, and low cost.

What should be paid attention to when splicing optical cables

Preparation of the end face

The preparation of the fiber end face includes stripping, cleaning and cutting. A qualified fiber end face is a necessary condition for fusion splicing, and the quality of the end face directly affects the quality of fusion splicing.

Stripping of optical fiber coating

Master the flat, stable and fast three-character fiber stripping method. "Ping" means keeping the fibers flat. Pinch the optical fiber with the thumb and index finger of the left hand to make it horizontal. The exposed length is 5cm. The remaining fiber is naturally bent between the ring finger and the little finger to increase strength and prevent slipping. "Steady" means that the fiber stripping pliers should be held firmly. "Fast" means that the fiber should be stripped quickly. The fiber stripping pliers should be perpendicular to the fiber, and the upper part should be tilted inward at a certain angle, and then gently clamp the fiber with the jaws, and push it out along the fiber axis with force with the right hand. The whole process Be natural and fluid, in one go.

Bare Fiber Cleaning

Bare fibers should be cleaned in the following two steps.

Observe whether the coating layer of the stripped part of the optical fiber is completely stripped off. If there is any residue, it should be stripped again. If there is a very small amount of coating layer that is not easy to peel off, use a cotton ball dipped in an appropriate amount of alcohol, and wipe it off gradually while dipping.

Tear the cotton into flat fan-shaped small pieces, dip in a little alcohol (it is better to pinch with two fingers without overflow), fold it into a "V" shape, clamp the stripped optical fiber, and wipe along the optical fiber axis, striving for a success A piece of cotton should be replaced in time after being used for 2-3 times, and different parts and layers of cotton should be used each time, which can not only improve the utilization rate of cotton, but also prevent the double pollution of the fiber probe.

Cutting of Bare Fiber

Cleaving is the most critical part in the preparation of optical fiber end faces. A precise and excellent cutter is the foundation, and strict and scientific operating specifications are the guarantee.

Choice of cutter

There are two kinds of cutters: manual (such as Japan CT-07 cutter) and electric (such as Ericsson FSU-925 cutter). The former is easy to operate and reliable in performance. With the improvement of the operator's level, the cutting efficiency and quality can be greatly improved, and the bare fiber is required to be shorter, but the cutter has higher requirements on the ambient temperature difference. The latter has higher cutting quality and is suitable for working under cold conditions in the field, but the operation is more complicated, the working speed is constant, and the bare fiber is required to be longer.

It is advisable for skilled operators to use manual cutters for fast optical cable splicing or emergency rescue at room temperature; on the contrary, beginners or when working in colder conditions in the field, use electric cutters directly.

Code of Practice

Operators should undergo special training to master the essentials of action and operating specifications. First of all, clean the cutter and adjust the position of the cutter. The cutter should be placed stably. When cutting, the movement should be natural and stable. Don’t be heavy or anxious to avoid broken fibers, bevels, burrs, cracks and other bad end faces. In addition, learn to "play the piano", rationally distribute and use your right hand fingers, make them correspond to and coordinate with the specific parts of the cutter, and improve the cutting speed and quality.

Beware of end-face contamination

The heat-shrinkable sleeve should be inserted before stripping, and it is strictly forbidden to insert after the end surface is prepared. The time of cleaning, cutting and welding of bare fibers should be closely connected, and the interval should not be too long, especially the prepared 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 not be polluted.

Fiber splicing

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.

Choice of fusion splicer

Fusion splicing equipment with battery capacity and precision should be equipped according to the requirements of optical cable engineering. According to the author's experience, the Japanese FSM-30S arc welding machine has excellent performance, stable operation, high welding quality, and is equipped with a dustproof windproof cover and a large-capacity battery, which is suitable for various large and medium-sized optical cable projects. The Siemens X-76 fusion splicer is small in size, easy to operate, equipped with a simple cutter, the battery and the main machine are integrated into one, easy to carry, slightly worse in precision than the former, and smaller in battery capacity, suitable for small and medium-sized optical cable projects.

Splicing procedure

Before splicing, according to the material and type of the optical fiber, set the key parameters such as the optimal pre-melting main melting current and time, and the amount of fiber feeding. During the welding process, the welding?quot; V" shaped groove, electrodes, objective lens, welding room, etc. should be cleaned in time, and the presence of bubbles, too thin, too thick, virtual melting, separation and other undesirable phenomena in the welding should be observed at any time, and attention should be paid to the tracking and monitoring results of OTDR , analyze the reasons for the above adverse phenomena in a timely manner, and take corresponding improvement measures. If virtual melting occurs many times, check whether the materials and models of the two optical fibers to be welded match, whether the cutter and the fusion splicer are polluted by dust, and check If there is no problem with electrode oxidation, the welding current should be increased appropriately.

Disc fiber

Disk fiber is a technology, but also an art. The scientific fiber coiling method can make the optical fiber layout reasonable, the additional loss is small, can withstand the test of time and harsh environment, and can avoid the phenomenon of fiber breakage caused by extrusion.

Quality Assurance of Optical Cable Connection

It is of great significance to strengthen the monitoring of OTDR to ensure the quality of optical fiber fusion, reduce the additional loss caused by the fiber coil and the possible damage to the optical fiber caused by the sealing box. During the entire splicing work, the four monitoring procedures of OTDR must be strictly implemented: 1) Real-time tracking and monitoring of each core fiber during the fusion splicing process to check the quality of each splicing point; Carry out a routine inspection to determine the additional loss caused by the fiber coil; 3) Before sealing the splicing box, conduct a unified test on all optical fibers to find out whether there is any missing test and whether there is extrusion on the optical fiber and the connector between the optical fiber reserved discs; 4 ) After sealing the box, perform a final inspection on all optical fibers to check whether the sealing box has damaged the optical fiber.