Preparation of a project checklist

Requirements to complete the installation of the cable network

·      Final inspection

·      Review of the test information in the cable network

·      Instructions for configuring and testing the communications system

·      Last documentation update

·      Update and completion of the restoration plan, storage of components and documentation
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Preparation of a project checklist
The final checklist of a project will consist of several points, all of them of great importance. Each point on the list requires a complete description that contains the place and time at which it will be necessary and the person responsible for that point. See Chapter 10 for a recommended checklist for the installation of a project. Components such as cables and cable network hardware must have indications regarding suppliers, locations, dates and times of delivery and even, sometimes, the mode. Special equipment for installation must also be planned. Notes on what should be purchased and what will be rented should be included. If the workplace is not safe and the installation will take more than one day, it may be necessary to have security guards in the workplace.

A work plan should be developed that indicates the specializations that will be needed, as well as the place and time. The facilities of the external plant (OSP) usually have a work team in charge of pulling the cables, in particular those that require special facilities such as direct buried cables, those of aerial or underwater laying, other equipment in charge of the splices and maybe one more to perform the tests. OSP installers usually do only part of the job because they need not only skills and training to handle specialized equipment, such as fiber optic fusers or OTDRs, but also installation practices: climb the poles or run the cables through the plow. The contributions of the installation teams can help determine the approximate time needed for each stage of the installation and what are the possible inconveniences that can affect the planning.

To provide specifications about the cable

To provide specifications about the cable, it is necessary to know how many fibers are included in each cable and what type they are. It is important to understand that fiber, especially single-mode fiber used in almost all OSP facilities, is economical and installation is expensive. The installation of an OSP cable can cost a hundred times more than the cost of the cable itself. Choosing a single-mode fiber is easy; The 1300 nm basic single-mode fiber (called G.652 fiber) is suitable for everything except for long links or for links that use wavelength division multiplexing. It is possible that these installations require a special fiber optimized from 1500 to 1600 nm (G.653 or G.654). In internal or campus-level cable networks, the laser-optimized OM3 50/125 multimode fiber is probably the best choice for any multimode fiber laying in OSP, given its lower attenuation and more bandwidth elevated allow most networks to work better.

Adding more fibers to a cable will not increase the cost of the cable proportionally; The basic cost of building a cable is fixed, but adding fibers will not increase its price much. Choosing a standard design will also save costs, as manufacturers can have that cable available in stock or build it while building others of similar design. The only thing that represents the true cost of adding more fibers is the cost generated by adding additional splices and terminations, which is still low compared to the total cost of the installation. Also, remember that having additional fibers for future extensions, for backup systems or for individual fiber breakage cases can save you many headaches in the future.

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Water or moisture protection and reinforcement elements are common characteristics of external plant cable networks. The necessary strength of the cable depends on the installation method (see below). The water and moisture resistance of all cables installed outdoors should be evaluated. Until recently, most people chose a gel-filled cable, but now, dry cables that block water are widely available, and many users prefer them. These cables use a tape that absorbs water and energy that propagates and seals the cable if water enters. Installers especially prefer dry cables since it is not necessary to perform the cumbersome and boring task of removing the gel that is used in many cables, which greatly reduces the preparation time of the joints or terminations.

Let's first analyze the communications system

Before starting to design a fiber optic cable network, it is necessary to determine together with the end-user or the owner of the network where the network will be built and what communication signals it will carry. Most contractors are familiar with internal plant networks, in which computer networks (local area networks or LANs) and security systems use structured cabling systems that are built based on well-defined industry standards. Once the wiring leaves the premises, even on short distance links such as a LAN network at the campus level or a metropolitan area network, the requirements for fiber and cable types vary. Long-distance links for telecommunications networks, CATV or utility companies have other stricter requirements that must be considered and are necessary to allow longer high-speed links.

However, although the contractor usually thinks first of the wiring requirements, the design itself begins with the analysis of the communications system requirements established by the end-user. First, attention should be paid to the types of equipment necessary for communication systems, the speed of the network and the distances it will cover, and then everything related to the cable network is analyzed. The equipment of the communications system will determine if fiber is needed or preferred and, in that case, what type of fiber.

Internal plant networks

Indoor wiring systems are designed to transport computer networks using Ethernet technology, which currently operates at a speed of between 10 megabits and 10 gigabits per second. Other systems can transport security systems with digital or analog video, perimeter alarms or access control systems, which generally operate at a low speed, at least as regards fiber. The telephony systems in the internal plant can be transported by means of twisted-pair cables or, what is more, common today, by means of LAN wiring with voice over IP (VoIP) technology.

In general, internal plant networks are short distance; They usually have less than 100 meters that are established as a limit for standardized structured cabling systems that allow the use of twisted-pair copper or fiber optic cabling. In turn, networks internal plant that is connected to a LAN at the campus level used in industrial complexes or institutions, have a backbone ( backbone ) that reaches a distance of 500 meters or more and uses fiber optics.

The networks in the internal plant usually operate with multimode fiber. Multimode systems are cheaper than single-mode systems. This is not because the fiber or cable is cheaper (they are not), but because the large core of the multimode fiber allows the use of LED or VCSEL sources in the transmitters, which lowers the cost of Electronic devices Often astute designers and end-users utilize both multimode fibers and single-mode in cable core network ( backbone ), called hybrid cables because the single-mode fibers are very economical and provide an almost unlimited possibility of expanding the systems.

External plant networks

Telephone networks are usually mainly external plant systems (OSP) that connect buildings both at short distances of a few hundred meters and at distances of hundreds of thousands of kilometers.

 In telecommunications, the data transmission rate is usually 2.5 to 10 gigabits per second, and very powerful lasers are used that only work on single-mode fibers. The tendency of telecommunications is to take the fiber directly to commercial buildings or homes since, at present, the signals are too fast for twisted-pair copper cables.

The CATV also uses single-mode fiber systems based on hybrid fiber-coaxial (HFC) or digital systems, in which the backbone ( backbone ) is fiber and the connection to the home is a coaxial cable. The coaxial cable is still used in the CATV since it has a large bandwidth. Some CATV providers discussed the possibility of taking fiber to homes or even tried, but the economic aspect still does not convince them.

In addition to telecommunications and CATV, there are many other applications of fiber in OSP. Smart highways are equipped with security cameras and signs and/or signals connected by means of fiber optics. Security control systems in large buildings, such as airports, commercial or government buildings, casinos, etc., are usually connected by fiber due to the large distances in these places. As in other networks, multimode fiber is usually used in internal plant installations, while single-mode fiber is used in the external plant to be able to make longer links.

Metropolitan area networks that belong to and are operated by cities can carry different types of traffic, including surveillance cameras, emergency services, education systems, telephone systems, LAN, security systems, supervision and control systems. transit and even, sometimes, the traffic of commercial interests when using a rented bandwidth that works by means of dark fibers or fibers that belong to the city. However, given that the majority of these networks are designed to allow longer links than internal or campus level facilities, single-mode fiber is the chosen one.

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For all installations, except in the internal plant, fiber is the chosen means of communication, since its capacity to allow greater distances and bandwidth position it as the only option or the one that is significantly less expensive compared to the cable Copper or wireless network. Only inside a building is the possibility to choose, and the economy, network architecture, and tradition of using copper cables in buildings influence that choice. Next, we will analyze in more detail the choice between fiber, copper and the wireless network.

Most fiber optic connectors are manufactured

Most fiber optic connectors are manufactured so that the fiber is mounted on a protruding splint, called a "male" style connector. Two male connectors are attached using a coupling adapter that keeps the splints aligned and allows them to be in the center. If connectors like these are being tested and the test equipment has interfaces that fit these connectors, the single wire reference (OFSTP-14 Method B) can be used. This method is the simplest method and is generally considered the preferred method since connections are not included when establishing the 0 dB reference.

After establishing a reference, the launch cable is disconnected from the meter, but not from the source. The reference launch cable should never be disconnected from the source after the reference is established, in order to ensure that the launch power remains constant. The receiving cable is connected to the meter and then both reference cables are connected to the cable to be tested. The loss reading will include both connections to the cable under test and the loss of the fiber and any other component in the cable.

If the test equipment has an interface for a connector of another style, so that the connectors on the cables being tested cannot be attached to the instruments, a two-wire reference method can be used (OFSTP-14 Method A ). The reference cables must be hybrid cables with connectors at one end to fit the interface of the instruments and the other end to fit the connectors on the cable to be tested. The 0 dB reference is established by joining the two reference cables to the instruments and connecting the other ends with a coupling adapter. After setting the reference,

The loss reading will include both connections to the cable being tested and the loss of the fiber and any other component in the cable minus the loss of the connection between the two reference cables when establishing the reference. Therefore, the measured loss obtained with the two-wire reference will be less than the single-wire reference for the connection that is included when establishing the reference. The uncertainty of this loss of connection included in the reference also adds to the uncertainty of the loss measurement of any cable that is tested in this way.

Some fiber optic connectors have "male" and "female" style connectors, in which one has a splint that protrudes while the other has a female plug or receptacle. Some have alignment pins only on one side, such as the MTP connector where the pins are used on the side of the female socket. They are generally used with male plugs on both ends of the connecting cables and female plugs or receptacles on permanently installed cables that terminate in racks or sockets.

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Either of these two connector styles can only be coupled to an appropriate connector style, which makes it difficult to make a reference of one or two wires. The solution is a three-wire reference (OFSTP-14 Method C), in which the hybrid cables connected to the instruments for the reference cables terminate in male plugs and a third cable terminated in female plugs is inserted between them to create a 3 wire reference. After setting the reference, the two reference cables are disconnected from the third cable in the middle, and the cable to be tested is inserted between them instead of the reference cable.

As mentioned earlier, the loss reading will include both connections to the cable being tested and the loss of the fiber and any other component in the cable minus the loss of the two connections between the third reference cable and the two reference cables to the set the reference. Since generally, the third cable is only a short length fiber with connections at each end, fiber loss can be ignored. Therefore, the loss measured with the three-wire reference will be less than the single cable reference for the two connections included when setting the reference. The uncertainty of these two connection losses included in the reference also adds to the uncertainty of the loss measurement of any cable that is tested in this way.

Although this three-wire method has the greatest uncertainty, it is the only method that works for any connector and test equipment. Therefore, it has become the preferred method in several international standards.

The mechanical splicing process

Fiber preparation

The splicing process is almost the same for all types of mechanical splices. The first step is to peel, clean and cut the fibers to which the splicing will take place. You must peel the fiber coating to expose the necessary length of the bare fiber, clean the fiber with a suitable cloth, cut the fiber following the indications of the precision cutter you are using; If you use a precision cutter like the ones that come with the fusers, you will achieve more consistent splices and lower losses.

How to perform the mechanical splice

Place the first fiber in the mechanical joint. Most splices are designed to limit the depth at which the fiber is inserted through the length of bare fiber. Secure the fiber in place if the fibers are separated; Some splices secure both fibers at the same time. Repeat these steps for the second fiber.
You can optimize with a visual fault locator, which is a laser checking source, the losses of a
mechanical splice if the fiber ends to be spliced ?? can be seen. Gently remove one of the fibers,
rotate it slightly and reinsert it until the visible light is minimal, indicating the least loss.

How to make good splices

To constantly achieve splices with low losses, proper technique and maintenance of the equipment in good condition are needed. Of course, cleanliness is an important issue. Fiber peelers should be kept clean and in good condition, and should be replaced when damaged or worn. Precision cutters are the most important since the secret of good splices (whether fusion or mechanical) is to obtain good cuts in both fibers. Keep the precision cutters clean and the carbide tip lined pencil edge, and replace it regularly. You must properly perform the corresponding maintenance of the fusers and adjust the melting parameters according to the fibers that are spliced. For mechanical splices, It is important to lightly press the fiber to hold the ends together while securing them. If possible, use a visual fault locator to optimize the splice before securing it.

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Splice Protection

To protect them from the environment and from deterioration, the joints need a protective sheath. 

They are usually placed in a splice tray, which is then placed inside a splice box in the external plant facilities or in a connection panel in the internal plant facilities. Within the splice closures and at each end, those cables that have shielding or resistance elements must be properly 

grounded.

The connectors can be installed directly on most types of cables

The connectors can be installed directly on most types of cables, including simplex cables of tight structure, duplex cables ( zip cord ) and breakout cables, in which the aramid resistance elements are crimp or glued to the body of the connector to create a strong connector. The connectors can be attached to the 900-micron fibers of tight structure within the distribution cables, but the termination is not as resistant as that of the jacket cables, so they must be installed in connection panels or boxes for protection.  The termination of the 250-micron fibers of tight structure in loose structure cables can be complicated unless they have a reinforcement called a kit to protect the termination of the fiber ( breakout kit ) or bifurcation kits ( furcation kits ), where each fiber It is dressed by a larger plastic tube. In general, the fiber termination type and loose cable type ribbon ( ribbon ) is made with a connectorized fiber optic cable ( pigtail ).

The cables can be laid with the connectors already installed if and only if you can deal with two issues. First, the length of the cable must be exact. If it is too short, you should lay another longer cable (it is not profitable to make splices). If it is too long, you will have wasted money and will have to store the excess cable. Second, the connectors must be protected. Some cable and connector manufacturers offer protective covers for the connectors, but you must still be very careful when laying the cables.   You should consider placing the terminations at one end and pulling another end without terminations so as not to put the connectors at risk. Now there is a growing trend: install previously terminated systems with the MTP 12 multifiber connector; It is a very small connector, not much larger than an ST or SC connector, but ends up to 12 fibers. Manufacturers sell multifiber cables that already have MTP connectors installed that connect to the pre-terminated connection panels with ST or SC connectors.   
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Terminations for multimode fiber
For multimode fibers, there are several types of terminations available. Each version has its advantages and disadvantages, so learning more about how each one works will help you decide which one to use.

Terminations for single-mode fiber
Single-mode fiber requires different connectors and polishing techniques, which are best performed within a factory. As a consequence, the termination of the single-mode fiber is done by connecting it
with a factory-assembled pigtail fiber cable . The termination of the single-mode fiber requires special connectors, with much more splint tolerance, especially the groove to hold the fiber. To polish it,  special granulated sandpaper with diamond particles is required, it must be done on a flat pad with the polishing mixture to achieve a low reflectance.   If you know how to do it, you can place the single-mode connectors in the field. But there will be greater loss and greater reflectance.

Fiber optic sensors are possible to use fiber hoses

Optical fibers can be used as sensors to measure tension, temperature, pressure and other parameters.

The small size and the fact that no electric current circulates through them gives certain advantages
over the electric sensor.

Optical fibers are used as hydrophones for earthquakes or sonar applications. Hydrophonic systems with more than 100 sensors have been developed using fiber optics. Hydrophones are used by the oil industry as well as the navies of some countries. The German company Sennheiser developed a microphone that

worked with a laser and optical fibers.

Fiber optic sensors for temperature and pressure have been developed for oil wells. These sensors can work at higher temperatures than semiconductor sensors. Another use of fiber optic as a sensor is the optical gyroscope used by the Boeing 767 and the use in hydrogen microsensors.
illumination
Another use we can give to the optical fiber is to illuminate any space. Due to the advantages that this type of lighting represents in recent years it has begun to be widely used.
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Among the advantages of fiber lighting we can mention:
Absence of electricity and heat: This is because the fiber only has the ability to transmit the light beams in addition to the lamp that illuminates the fiber and is not in direct contact with it.
You can change the lighting color without changing the lamp: This is because the fiber can transport
the light beam of any color regardless of the color of the fiber.
With a lamp you can make a wider illumination by means of fiber: This is because with a lamp you can illuminate several fibers and place them in different places.
More fiber-optic applications
It can be used as a waveguide in medical or industrial applications where it is necessary to guide a
a beam of light to a target that is not in the line of sight.
The optical fiber can be used as a sensor to measure tensions, temperature, pressure as well as other
It is possible to use fiber hoses together with lenses to make long and thin viewing instruments

called endoscopes. Endoscopes are used in medicine to visualize objects through a small hole.

Industrial endoscopes are used for similar purposes, such as to inspect the interior of turbines.
Optical fibers have also been used for decorative uses including lighting, Christmas trees.
Subscriber lines
Optical fibers are widely used in the field of lighting. For buildings where the light can be collected on the roof and taken by a fiber optic to any part of the building.
It is also used to trick the sensory system of taxis causing the meter (some call it counters) does
not mark the actual cost of the trip.
It is used as a component in the manufacture of translucent concrete, an invention created by the
Hungarian architect Ron Losonczi, which consists of a mixture of concrete and fiber optics forming a new material that offers the strength of the concrete but additionally, presents the particularity of letting the light wide.

parameters.

Data link performance and link optical power budget

Measurement of data transmission quality

As with copper or radio cable transmission, the performance of an optical data link can be determined by how it transmits the data; how the reconverted electrical signal that leaves the receiver adapts to the transmitter input.

The ability of any fiber optic system to transmit data basically depends on the optical power in the receiver, as illustrated in the image above, in which the erroneous bit rate (BER) of the data link is shown as a function of the optical power in the receiver. (The wrong bit rate is inverse to the signal to noise ratio, for example, a high bit rate implies a poor signal-to-noise ratio). In the case of insufficient power or excess power, a high bit rate will be generated. If there is excess power, the receiver amplifier becomes saturated; and if there is insufficient power, noise becomes a problem since it interferes with the signal. The power of the receiver depends on two basic factors: how much power the transmitter throws on the fiber and how much power is lost by attenuation in the fiber optic cable network that connects the transmitter with the receiver.

Link optical power budget

The budget of the optical power of the link is determined taking into account two factors: the sensitivity of the receiver (which in turn is determined in the wrong bit rate curve as illustrated above) and the output power of the transmitter in the fiber. The minimum power level that generates an acceptable erroneous bit rate determines the sensitivity of the receiver. This transmitter power coupled to the fiber determines the transmitted power. The difference between these two power levels determines the loss margin (optical power budget) of the link.

High-speed data links such as gigabit local area networks or 10gigabit Ethernet over multimode fiber have decrease factors in fiber bandwidth power caused by the dispersion of digital data pulses. Old OM1 62.5 / 125 fibers generally operate on short links while transmissions through OM3 fiber optimized for 50/125 lasers are for greater distances. Even long-distance single-mode fiber links may have limitations caused by chromatic dispersion or polarization mode dispersion.

If the link is designed to operate at different bit rates, it is necessary to generate a performance curve for each bit rate. Since the total power in the signal is a function of the pulse width and this varies depending on the bit rate (at a higher bit rate, shorter pulses), the sensitivity of the receiver will cause degradation at high bit rates.

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The manufacturers of systems and components for data links specify for each type of link, the sensitivity of the receiver (maybe a minimum required power) and the minimum power coupled to the fiber from the source. The standard values ​​for these parameters are shown in the following table. In order for the manufacturer or who designs the system to test them properly, it is necessary to know the test conditions. For components for data links, these conditions include data input frequency or bit rate and duty cycle, power source voltage and the type of fiber coupled to the source. For the systems,

The characteristics of fiber optic

Optical fiber is a dielectric waveguide that operates at optical frequencies. Each filament consists of a central plastic or crystal core with a high refractive index, surrounded by a layer of similar material with a slightly lower refractive index.

When the light reaches a surface that borders a lower refractive index, it is largely reflected, the greater the difference in indices and the greater the angle of incidence, then there is talk of total internal reflection.

Inside an optical fiber, the light is reflected against the walls at very open angles, so that it practically advances through its center. In this way, the light signals can be guided without loss over long distances.

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Throughout the entire creation and development of the optical fiber, some of its features have been changing to improve it. The most outstanding features of fiber optic today are:

• Stronger coverage: the cover contains 25% more material than conventional covers.
• Dual-use (indoor and outdoor): The resistance to water and ultraviolet emissions, the resistant cover and the extended environmental performance of the optical fiber contribute to greater reliability during the life of the fiber.
• Greater protection in humid places: The intrusion of the moisture inside the fiber with multiple layers of protection around this one is combated, which provides the fiber, a greater useful life, and reliability in humid places.
• High-density packaging: With the maximum number of fibers in the smallest possible diameter, a faster and easier installation is achieved, where the cable must face sharp bends and narrow spaces. A cable with 72 super dense construction fibers whose diameter is 50% smaller than that of conventional cables has been achieved.

Optical transmission system with dynamic compensation of transmitted power.

A fiber-optic system is proposed for transmission with dynamic power compensation. This system comprises a transmission line having at least 1 optical fiber amplifier. It is planned to connect an optical amplifier with a stabilized coefficient. gain to the input of the line and this amplifier contains a local generator capable of emitting an auxiliary compensation wave, the length of which is located in the gain band of each amplifier with an optical fiber in this line. The invention is applied in networks of fiber optic transmission of information.

Dispersion-compensating optical fiber.

An optical fiber that compensates for dispersion has been developed. This fiber can be used. connected to an optical fiber having chromatic dispersion at the transmitted wavelength, in order to eliminate the latter almost completely. The developed fiber contains a core made of quartz-based glass and a sheath formed on the surface of the core also from the quartz-based glass. A protective layer of polymer is formed over the shell. The diameter of the compensating fiber is <250 µm. External coating thickness =20 µm. Coverage m. executed two-layer.

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Optical fiber with controlled dispersion.

An optical fiber with controlled dispersion is proposed in which control is carried out by changing the wavelength of zero-dispersion along the fiber length. Installed optim. dispersion control mode for the case in which the upper and lower wavelength ranges of zero-dispersion are widely spaced and are asymmetrically located relative to the operating wavelength. The use of such a fiber in communication networks can reduce signal distortion during transmission.

Long distance fiber optic with protective plastic pipes

The advantages of laying optical cables by blowing in protective plastic pipes are considered. 300 km long fiber optic transmission line connecting St. Petersburg with Lyuban and Luga is presented. When laying the lines, the considered method was used.

Measuring technique. Fast tunable laser with a range of 1.5 microns.

Firm BFI Optical GmbH (Germany) released the LD model 6428, which provides the possibility of quick wavelength tuning in a range from 1500 to 1575 nm, which has high stability and performance. The tuning speed of its wavelength can reach 100 nm / s with a resolution of ~ 1 nm. The output power of the generator with an LD of this model is stable in the range from 1520 to 1570 nm and is 6 dBm (4 mW). When tuning the wavelength in the entire specified range, the absence of mode jumps is guaranteed. Instability of the established wavelength in time <100 MHz in 24 hours
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Long-distance fiber optic with protective plastic pipes

The advantages of laying optical cables by blowing in protective plastic pipes are considered. 300 km long fiber optic transmission line connecting St. Petersburg with Lyuban and Luga is presented. When laying the lines, the considered method was used.

Sidestream injection synchronization using non-degenerate four-wave mixing in an LD with a distributed OS.

We experimentally demonstrated the synchronization of side-band injection between 2 LDs with a distributed OS, in which non-degenerate four-wave mixing with a high degree of saturation is used. Theor received confirmation. the assumption that injection synchronization takes place only if the frequency difference between the master and slave LDs is> 200 GHz with respect to the diversity of the Fabry-Perot LD modes. The experimental scheme is given. installation.

A radiation source module with a phase synchronization loop to form a coherent optical beam.

An optical module with a phase synchronization loop is presented, designed and manufactured for coherent optical beam formation systems. Beam Forming Devices m. used in multipath mobile communication systems with phased arrays. The module uses a phase synchronization loop with a tuning range of ~ 7-14 GHz.

On the possibility of generating and amplifying optical radiation at a wavelength of 1.3 μm in fiber optical fibers based on neodymium-doped quartz glass

The structure of a multilayer fiber waveguide is studied, which allows one to suppress radiation at a specific wavelength. It is shown that based on such a fiber made of ordinary quartz glass doped with neodymium ions and with appropriately selected parameters, fiber lasers and optical pulse amplifiers at a wavelength of 1.3 μm can be obtained.

Special optical fibers

As already noted in the introduction, OMs are currently widely used not only in FOSP but also in various fiber-optic sensors (VOD) of physical quantities and in fiber-optic devices (HEU). The specificity of this application requires the creation of OM with special properties. Among these special optical agents, formed mainly (like telecommunication optical agents) based on highly pure silica glass, are primarily: optical agents preserving the polarization of radiation; active agents; radiation-resistant OM and microstructured OM. Below, we consider the main characteristics of these OMs and the technology for preparing blanks for these OMs, the fibers themselves are pulled from the blanks on a conventional exhaust system.
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OBs preserving the polarization of radiation

The light propagating in single-mode fibers can be represented as the sum of two polarization modes. Each polarization mode propagates parallel to the fiber axis with its own phase and group velocity values. The phase front of the modes is flat, and the normal to the plane of the phase front is parallel to the fiber axis. The spatial distribution of fields in the polarization fiber modes is the same (Gaussian), and they differ in that they are polarized orthogonally, as can be seen from Fig. 6.1. In an ideal OB, these modes should propagate with the same velocities, i.e. must be degenerate.

However, in a real fiber, some defects are possible: the ellipticity of the core, its misalignment with the fiber axis, microbeads, various non-isotropic stresses lying in the plane of the perpendicular axis of the aircraft, inhomogeneities along the fiber length, etc. All these defects lead to different propagation velocities of modes orthogonal in polarization, and the phase velocities of these modes are inversely proportional to their SP. As a result of this, a phase delay R (the difference between the phase incursions of the modes) arises between the polarization modes. The length of the OM, at which the phase delay is 2, is called the runout length. In modern high-quality organic matter, the run-out length ranges from 10 cm to several meters. Therefore, we can talk about the inherent OM birefringence (DLP), which is written as:

where B - DLP, which is the difference between the PP of two polarization modes (Dn = n slow. - n fast. ), Lb is the beat length at a wavelength l. Thus, in telecommunication OMs, Dn is small in comparison with the difference between the PPs of the core and shell materials; therefore, polarization dispersion in OMs is only spoken at high transmission rates (> 10 Gbit / s). However, it is impossible to transmit polarized, in particular, linearly polarized radiation over telecommunication OBs over considerable distances.

There are two different approaches to the creation of organic matter preserving the polarization of radiation: these are fibers with a small DLP (respectively, a large beating length) and fibers with a large DLP, which is much larger than the DLP characteristic of a conventional AC.

Consider several options for the construction of fiber optic links.

FOCL inside one building. In this case, a two-fiber OK (“Noodle” type) is used for communication, which, if necessary, can be laid in the PND-32 tube under a raised floor or along walls in decorative boxes. All work can be done by the customer himself if the supplied cable is terminated with appropriate connectors.
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FOCL between buildings is built with a wok laying either along with the wells of cable communications or by hanging a wok between supports. In this case, it is necessary to ensure the coupling of a thick multi-fiber cable with optical transceivers. For this, cable sleeves are used in which the ends of the wok are cut, the fibers are identified and the fibers are terminated with connectors corresponding to the selected transceivers. This work can be done in several ways.
You can order a wok in a special performance Break-Out. This is a more expensive option, but you can immediately terminate the cable with optical connectors, remove terminated modules (cords similar to mounting wires) from the coupling and connect them to the transceiver equipment.
Optical cords with pigtail connectors can be welded to the fibers cut into the cable box. The length of the pigtail is selected for reasons of convenience for the user (for example, 3 m).
It is possible to terminate the fibers with connectors and plug the connectors from the inside into optical sockets (coupling) mounted in the wall of the cable box. Outside, an optical cord connector is inserted into the coupling leading to the transceiver equipment.
There are other ways to connect the wok with optical transceivers. Each method has its own advantages and disadvantages. In the practice of VIACOM OPTIC specialists, the third method has spread, since it is economical, reliable, provides low insertion optical losses through the use of sockets and connectors with ceramic elements, and is also convenient for users.

Special mention should be made of the need for optical cross-connect.

It should be noted that in recent years several methods for splicing optical fibers have been developed. Universal is considered a method of splicing fibers by welding on a special apparatus. Such devices are produced by firms: BICC (Great Britain), Ericsson (Sweden), Fujikura, Sumitomo (Japan). The high cost of welding machines has led to the creation of alternative technologies for splicing optical fibers.

Announcement - Fiber Optic Installer Certification

The Fiber Optic Installer Certification Course provides participants with the knowledge of installation, connectorization, splicing, testing and measurements of multimode and single-mode optical fiber. They will become experts in the installation of connectors, and mechanical and fusion splices.

Participants will have the option of taking the Fiber Optic Installer (FOI) certification exam of the International Association of Electronics Technicians (ETA-I, accredited by the International Certification Accreditation Council - ICAC). This course will provide participants with the skills to work in a cell phones, cable TV, and communications companies that install, test and maintain fiber optic networks.

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Course Level: Introductory to intermediate

Course Level: Introductory to intermediate

Course duration: 4 days (50% theoretical, 50% practical)

Dates: February 9, 16, 23 and March 2

Prices: $ 325 for one day, $ 625 for 2 days, $ 925 for 3 (no IVU is charged)

Optional: $ 150 for the ETA-International Certification exam

$ 100 for the preparatory session for the ETA-I exam

$ 25 Certificate of Continuing Education (30 HC)