10 good practices for working with fiber optics

1. Cleaning. Cleaning tools for fiber optic installations

Possibly one of the most important aspects to take into account when working with fiber optics is cleaning.   The optical fiber is not affected by electromagnetic interference, but it is very sensitive to humidity and dirt.

A simple rub on the connector surface can even cause several dB of loss or attenuation in the system. There are different products on the market for proper cleaning of fiber connectors. Although the most common is still a paper gauze and isopropyl alcohol.

2. Order. Color codes

Related to the previous point (since they go hand in hand) we have the order. The complexity of a fiber cable increases as the number of fibers in the same cable increases (reaching 512 FO).

The fibers are organized in microtubes inside a cable, these microtubes follow a color code to know at all times what is the numerical relationship of the fibers. There are several standards and color codes, depending on the type of cable and its modularity.

Maintaining the correspondence of the fibers when making a splice requires a high degree of order and discipline.   Plans or designs should always be followed so as not to make mistakes.

3. Watertightness. Proper sealing of the cable entry.

The best way to ensure that the fiber (fusions and connectors) maintains its properties without introducing attenuations in the system, is tightness. Once the fusion has been carried out or they face two connectors, the most appropriate thing is not to interfere with or allow external agents to interfere with them.

The elements to protect the fiber, from interior boxes to exterior boxes must have a level of tightness in accordance with the environmental exposure they may suffer. The IP XY (internal protection) standard defines different levels of protection against ingress of (X) dust and (Y) liquids.

One of the weakest parts against sealing, is usually the entry of cables in the boxes and the closure of the box itself.  You have to be extremely careful and follow the manufacturer's advice so that these parts are well sealed.

4. How to measure correctly. Gauges and measurement type, potentiometers / reflectometers

Measurement of a fiber optic system is a complex task and can be done in several ways and with different tools. A system must meet minimum and maximum power losses.

Potentiometers can be used to check the attenuation of the system, for this a source or transmitter inserts a light beam at a certain power at the beginning and at the end a power meter is placed that measures the incoming light beam power, from this way the difference between the input and output values ​​is calculated.

Reflectometers introduce a light beam, but in this case they analyze the resulting signal that reflects or bounces along the system at the same point in the system. By means of reflectometry, the signals can be analyzed graphically, taking at a glance the losses that appear in it.

5. Accommodating the fibers. Bending radii, fiber types G652 G657

Once the fusion is made, the excess fiber optic remains unprotected / without cover (bare with a thickness of 900 microns) with a length of approximately 1 meter. This surplus must be accommodated correctly, in the trays where the fusions are housed, for this the fiber is rolled up and stored.

It is important to know that the fiber cannot bend excessively, since losses would appear.   There are different types of fiber and each one allows a minimum bend radius.

6. Cable Retention, Aramid / FRP Core

The fiber optic cable construction has a reinforcing element used to protect it from jerks once it is installed in a box. This reinforcement is inside the cable and separated from the tubes where the fibers are housed. It is used to fix the end of the cable to the box, in this way in case of pulling the cable from the outside, the cable does not come off and the fusions and / or connections are protected. For each cable and box a number of Newton meters is determined that must withstand the traction.

Two of the most commonly used reinforcing elements are aramid yarns, a polyamide with highly resistant properties and the FRP core, it is a reinforced fiberglass.

7. Risk prevention. Work at height.

This aspect of work is common with other sectors, but no less important.   The regulations for the protection and prevention of occupational hazards must always be followed.

There are some specific aspects to take into account when working with fiber, correct handling of the fibers; If they can jump into the eyes or get into the hands (wear safety glasses and gloves), the light from a fiber optic produced by the fiber light generators can seriously damage the eye, even if the light is invisible.

8. Specific and quality tools. Fuser and cutter.

Working with fiber optics requires knowledge of specific tools that are not used in other fields , the most prominent being the fusion splicer and cutter. The fusion splicer works with micron precision to join two fiber optic cores, for this purpose, by means of two electrodes, they fuse the ends of the fibers.

To achieve a correct fusion it is very important that the ends of the fibers are clean cuts, without edges or burrs. To achieve this precision in the cut, a special cutter is needed, which fixes the fiber and passes a high precision circular knife to leave the fibers ready for fusion.

9. Breakdowns. How to detect them

A fiber optic communications system is relatively more stable and secure against breakdowns, but like any system accidents and breakdowns can occur. The most common are cuts or lack of continuity, but losses can also appear due to twisting of the cable or bending of the fiber.

The best tool for detecting faults is the reflectometer, since it can locate with great precision the distance at which the cut or loss is.

10. Losses, insertion and return. Attenuators

There are several types of losses in a fiber optic installation, the most common or the ones that are given the most attention are insertion loss and return loss.

Insertion losses are those that occur when a new element is added to the system, it can be a fusion, connectors, splitter, etc. These elements reduce the power of the signal, and are calculated as the difference in power between the input of the element and its output.

Return losses are measured as the difference in signal strength between the input and the reflection or bounce of light caused by the element. The greater this difference means that the lower the reflection or rebound, that is, the better the element will be how does fiber optic work.