What factors affect the fiber fusion effect? Counting the construction of seven "sin"

The use of optical fiber for fiber fusion construction will be very convenient after being proficient, but there are many steps that need to be brought to our attention. Some steps that are inadvertently omitted or not in place may result in the final fusion. The result is not good.

Fiber splicing, connection, testing, and fault checking Many examples tell us that some simple decisions we make every day really make our fiber network performance worse. Let us take a look at what these seven sins are.

The first sin: not cleaning the fiber before welding

Strip the coating of the fiber and clean the fiber. This is the first step in splicing the fiber, but it is also a very important step. If the cleaning is not in place, it will cause a lot of trouble for the subsequent welding, such as dust burning, the fiber is offset at the fixed position of the V-groove, and eventually The splice loss becomes large. Therefore, you need to pay attention to the following points when cleaning the fiber:

a. Use alcohol with a purity of 99% or more

b. Change gauze or cleaning paper for each cleaning

c. Clean from the edge of the stripped portion of the strip

d. Wipe until the sound of “Q” or “Q” is issued and then wipe it several times.

Before the fiber is fused, it is very important that you clean it before cutting the fiber. This removes debris and other contaminants that may remain in the fiber stripping process.

Be sure to pay attention to cleaning and cutting. Nothing is cleaner than the newly cut fiber end face. Never clean after cutting. If you do it, it will stain the end face. This imposes an additional burden on the fusion machine during the pre-discharge phase, shortening electrode life, resulting in a non-linear joint with bubbles that reduces the mechanical strength of the joint and introduces additional losses.

When cleaning bare fibers, it is highly recommended that operators use fast-evaporating, non-flammable precision cleaning fluids. Commonly used alcohol (IPA) is both hygroscopic and flammable. IPA is susceptible to contamination due to bonding with water molecules in the air. Fusion engineers should look for other cleaning products that are certified. Better cleaning fluids are sealed and packaged in non-refillable containers to prevent cross-contamination. In addition, it is non-flammable, volatile, and free of water.

Second sin: improper use of cutting tools

Whether the fiber end face is smooth or not has an important influence on the performance of the splice or terminated fiber. In the past, fiber cutting knives were often used to manually cut fibers, which required the operator to be systematically trained and skilled. Now, with the development of technology, modern automatic cutting tools are already very common in the market. The new tool design uses a protective blade, a better ergonomic design, including an adjustable handshake, which can be cut in one motion. These tools both improve operator safety and protect the fiber. In general, automated cutting tools are an important tool to ensure that the fiber end face is qualified after cutting.

For these handheld tools, you need to clean them, which can reduce the occurrence of fiber breaks in the welding preparation. Clean these tools, especially the tools that peel off the skin. Wipe these tools with a fast-drying solvent and a lint-free cloth, carefully remove the oil, especially the dust on the fiber jacket and tight casing.

The third sin: no calibration before fiber fusion

Everyone knows that to keep the fusion splicer, the cutting tool and the V-slot cleaning, so that the electrodes do not accumulate calcium, but many experienced operators will notice that sometimes no matter how hard they try, they will never get what they want. Welding result. Sometimes the problem comes from the fact that the glass material is not ideal. Sometimes the electrode is not clean. If the problem cannot be solved, the fiber will be discarded. However, we have to say that these operators may judge the wrong reason.

It is very important to calibrate the fusion splicer. In particular, the strength or current intensity of the arc needs to be adjusted frequently to ensure proper size when welding, to ensure that the mechanical strength of the welded joint is strong enough and the optical performance is good enough. This is especially important when the air pressure changes or when working at high latitudes. In fact, the calibration work is very easy to do. For most fusion splicers, simply put the fiber on it, just like welding. However, when calibrating, you don't need to fuse, but you need to go to the maintenance menu of the fusion splicer, choose the option of arc calibration or arc back test, and the splicer will tell the operator how to calibrate step by step. After the calibration is completed, the fusion splicer will also remind you that the calibration is complete or if you need to retest the entire system. If it has not been calibrated before, the fusion splicer may need to be re-tested several times to adjust itself. The current, atmospheric density, and humidity indicators need to be self-adjusted to ensure performance.

The fourth sin: the micro-bend of the fiber

Micro-bending of the fiber is generally caused by excessive pressure on the fiber. Micro-bending of the fiber causes a drop in signal quality, and this problem is difficult to find by the naked eye unless it is checked by an OTDR.

What caused the fiber to bend slightly? It should be excessive pressure on the fiber. A common cause is too tight when fixing the cable. Other causes of microbending of the fiber may be caused by the position of the cable in the shaft of the device panel.

For fiber fusion, a good option is to use a transparent sleeve to package the splice points. This loose tube will be shaped into a transparent sleeve to form a tight package. These transparent sleeves are then placed in the terminal block and secured. The fixed knot will slide freely over the outer layer of the hard plastic sleeve. This avoids any squeezing of the fiber as it moves, causing many problems that are not necessary in the future.

The fifth sin: excessive bending of the fiber

All cables have their own minimum bend radius. Therefore, when constructing the cable, we must pay attention not to exceed the minimum bend radius of the cable to avoid damage to the cable and the fiber inside the jacket.

Over-bending occurs when the slack loop of the cable is too tight and placed on the undersized pedestal, hand hole. Products like "snow shoes" are used to help cable builders avoid the problem of over-tightening of the overhead expansion ring. Over-bending also often occurs when the constructor uses mouse ears or buckles to secure the overhead cable.

Over-bending can also occur in the splice tray. A common scenario is when a small splice tray is used with a 60mm weld sleeve, rather than a 40mm sleeve. The large sleeve will be too close to the edge of the splice tray, leaving no sufficient bend radius for the fiber.

What is the problem with over-bending? You can see the problem when you test with OTDR. Over-bending is often only found when testing at 1550 nm or 1625 nm. Most single-mode fibers operate at 1310 nm, which is less sensitive to bending. However, today more fiber systems use 1550nm and 1625nm wavelengths. These wavelengths are more sensitive to problems in the fiber. Those problems that are not visible with OTDR at 1310 nm may have significant problems at these two wavelengths, and the solution is to avoid over-bending.

Sixth sin: reuse of old wiping paper/cloth

Reusing wipes/cloths is a small loss of behavior because when a connector is cleaned with a wipe/cloth, the wipe/cloth is dirty and it will stain the oil on the hand. And the ash layer, if you use it to wipe other connectors, it will contaminate other connectors. Reusing a lint-free wipe/paper is not cost effective. In fact, it is likely that duplication of pollution will bring nightmare results to the network. Of course, if you really want to save money, you can buy a small wipe/cloth.

A good high modulus wipe should not be afraid of tearing, not afraid of breaking, not afraid of fluffing, and will not bring pollution to the end face of the connector. But many companies buy wipes that are low-modulus and sticky. The sharp end faces of the connectors can easily tear these wipes. Repeated use of these wipes will definitely contaminate the end faces of the connectors.

Wipes are not a very expensive item, compared to the cost of re-examining the problem on site. There are three important points in it. First, don't buy big ones and buy small ones. Second, don't buy large bagged wipes and buy those that make sure they are clean when used. Third, tell your team that all the wipes are thrown away once. You feel wasted, think about the extra cost you have to pay for it.

The seventh sin: no inspection and cleaning of the connector end face before installation

The connector end face is also a place that is highly susceptible to dust and oil contamination. Therefore, we should check and clean the fiber connector end face when installing the connector. The cost of a ferrule end face detector is less than the cost of two on-site repairs. Are you willing to spend a small amount of money to do a cleaning check beforehand or after a long time or a big price?

Avoid unnecessary costs from seven sins

The seven sins mentioned above are long-standing problems in fiber-optic communications. These problems slow down the fiber-optic network and often cause network failures. However, as long as the network construction personnel strictly follow the standard steps, add a little care. Can avoid these problems very well.