What kind of fiber optic?

When reading an article or when talking with someone about fiber optics it is important to know what fiber optic they are referring to. Not all fiber optic cables are the same. In this book we will focus on the optical fiber used in communications; however, it can also be used in lighting, in medical controls, in non-destructive tests and in the manufacture of sensors for physical measurements.

In the field of communications, there is the optical fiber for "external plant", which is used for telephone networks, cable television (CATV), metropolitan networks, services, etc., and the fiber used for the internal plant, that is, the one found in buildings and in various facilities. In the same way that "cable" can have many meanings - the optical fiber that is used for electric power, security, ventilation, heating and air conditioning (HVAC), closed-circuit television (CCTV), Local area networks (LAN) or telephony is not the same, which can generate great confusion for the beginner. Let's define some terms.

External plant

Telephone, cable television, and internet companies use fiber optic, which is almost entirely outside buildings and referred to as an external plant (OSP),   as it hangs from poles, it is underground, it goes through underground ducts or it can even be submerged underwater. Most cross long distances, ranging from a few meters to a few hundred kilometers.

Generally, the cables of the external plant have a very high amount of fibers, up to 288 or more. Cable designs have been optimized according to your application: duct cables are optimized to be tensile and resistant to moisture; underground cables are optimized to resist moisture and rodent damage; the aerial cables are in front of the continuous traction and extreme weather conditions, and submarine cables are optimized to resist moisture penetration. The installation requires special equipment, such as cable handles, and even trailers to transport huge cable reels.

The long distances involve spliced ​​cables since the cables are not made of lengths greater than 4-5 km. (2.5 - 3 miles), and most splices are made by fusion splices. Connectors (usually SC or LC) are spliced ​​at the end of the cable, turning them into connectorized fiber cables ( pigtails). After installation, all fibers and splices are tested with an OTDR (optical reflectometer in the time domain).

If this seems costly, you're right! Generally, the installer has a temperature-controlled vehicle, be it a truck, a trailer and/or a truck with a crane. Investing in fiber optic fusers, OTDR and other equipment can be quite expensive. Most of the telephony facilities in the external plant are carried out by the same telephone companies, while a small number of a large number of specialized installers perform cable television installation, public and municipal services.

Wiring in the internal plant

On the contrary, the wiring in the internal plant (wiring in buildings and other facilities) implies shorter distances, rarely greater than a few hundred meters, generally with less fiber per cable. Mostly multimode fiber is used, except in the case of the informed user who installs hybrid cable with multimode fiber and single-mode for future high bandwidth applications.

Practically no fusion splices are used in these types of facilities. The cables for the connection between buildings can be double-coated, one of polyethylene for the external plant over another of PVC, for installations in buildings that require cable coverings with fire-retardant properties. Today, connectors generally have less loss than splices, and connection panels provide greater flexibility for movements, additions, and modifications.

The most used connectors are those of type SC or ST, and those of type LC are beginning to be more popular. The terminations are made by installing connectors directly at the ends of the fiber, mainly through the use of splicing techniques with pre-polished adhesives or connectors. The tests are performed with a source and a meter, but each installer should have an indicator for light flashes to verify the continuity of the fiber and the connection.

Unlike the technician working in the external plant, the cable installer working in the internal plant (which generally also installs the power cable and the cat. 5/6 cable for LAN networks) probably makes a relatively minor investment in tools and equipment. There are thousands of wiring installers that perform fiber optic work; They discovered that it is not "a science", and that their small initial investment in training, tools and testing equipment is recovering rapidly.

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Installers

Not many installers perform both types of wiring: in external plant and in the internal plant. The companies that do it are generally large and have separate departments that perform each type of wiring with different personnel. Most contractors only perform wiring in the internal plant.

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Emission of a soliton wave from a nonlinear waveguide with a PTS cladding.
The results of numerical simulation of the emission of a soliton wave from an optical waveguide in which the sheath is made of a nonlinear material (polyacetylene para toluene sulfonate ( PTS )) are presented. This material with cubic non-linearity and self-focusing demonstrates a defocusing nonlinearity, which imposes restrictions on max. nonlinear gain changes. The influence of these restrictions on the emission of a soliton wave in the 1st transverse dimension is investigated. The results of numerical simulation for emission in 2 dimensions are proposed.

Emission of pulsed nonlinear surface waves and solitons by nonlinear waveguides with a gradient refractive index.
Fiber optic certified
The results of a study of pulsed beam propagation in nonlinear ion-exchange waveguides are presented. The limiting values ?? of the input power and film thickness were calculated to obtain emission using the variational method provided that there was no dispersion. Analytical expressions that can be obtained are obtained. used to calculate propagation characteristics.

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A short catalog of fiber-optic cables manufactured by Samara Optical Cable Company CJSC is presented. The equipment used in the production process is considered.

Temporary demultiplexing, which uses selective Raman amplification.

A fiber-optic transmission system is proposed in which a non-linear optical fiber demultiplexer is used. The time-multiplexed optical signal is transmitted along the first optical path, and the pump signal is transmitted differently. The pump pulses are synchronized with the pulses in the multiplexed optical signal, which highlighted. The amplification of the selected optical signal was carried out using a Raman amplifier.

 

40 Gb / s GaAs P - HEMT driver module for optical communications systems.

A 40 Gbit / s driver module was developed and implemented, which includes a set of 2 distributed amplifiers. The IC is made using 0.15 µm GaAs technology of transistors with high electron mobility. The characteristics of the module are given.

Converter/interface between RF and fiber optic cables.

The electronic-optical interfaces (in particular, converters) intended for connecting cables transmitting information on RF carriers to fiber-optic cables are considered. A duplex converter/interface is proposed, connecting several broadband RF cables with 2 optical ones.

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Compensation of optical dispersion.

A new method for compensating the dispersion of optical fibers is proposed. Compensation of optical dispersion is achieved using a polarizing beam splitter, which has 3 ports, which compensates for the dispersion of the fiber and devices that change the polarization mode. The principle of operation of a device that implements the proposed compensation method is considered.

Advances in Science and Technology in the Field of Fiber Optic Communications

A two-wave optical communication network with a ring architecture for a computer group.
A fiber-optic communication network is described for which the value of the message wavelength is part of the address. The network architecture has the form of a double ring, and the connection between the rings is carried out by tracing the signals along the wavelength. 2 wavelengths are used, one of which is used to transfer data inside the ring, and others to go to another ring.
Optical interconnects for multiple access with code division multiplexing and a communication network based on spectral multiplexing with temporary access.
A new architecture of optical interconnects based on the method of spectral multiplexing with time access is proposed. The possibility of using a similar architecture in communication systems with multiple access is considered. The use of spectral multiplexing with time access allows developing the concept of optical multi-station access with code division multiplexing, which will significantly reduce the cost of optical communication networks with a transmission rate of ~ Tbit / s.
Integrated information network on a combined (coaxial fiber) cable.
The structure of a duplex integrated information network in which hybrid cables (coaxial fiber) are used is considered. Functions, methods of formation, monitoring and control of 3 subsystems: KTV, data transmission between computers and cable telephone systems are developed in detail. Given that. system data
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The use of optical fibers of variable diameter and multichannel connectors for connecting fiber-optic communication networks using multimode and single-mode optical fibers.
The problem of making connections between optical fibers used in the composition of local fiber-optic communication systems and long-distance communication systems using single and multimode fibers is considered. The possibility of solving the problem using optical fibers or waveguides with a change in fiber diameter or waveguide width along the path and the use of multichannel devices for connecting optical fibers is shown. It is shown that the use of optical fibers with a variable diameter reduces the insertion loss when connecting systems.

Fiber Optical cable safety

Remember the last time you looked into your company's safety plan with a view to finding items related to
working with fiber in it?

Do not remember? This is not surprising, because in many organizations safety precautions when working with optical cables do not pay due attention.

Consider several aspects of safety when working with optical fiber: the classification of radiation sources according to their degree of danger to eyesight, methods of working with optical fibers and the use of chemicals.

As a result of the development of the industry for many years, we have several types of radiation sources of different power, operating at well-defined wavelengths (see table). Three types of fiber optic systems are used: LEDs, conventional lasers, and vertical-cavity laser (Vertical-Cavity Surface-Emitting Laser - VCSEL). There are several options for these three types of devices: lasers with a Fabry-Perot resonator and distributed feedback, as well as surface and end radiation LEDs. In addition, amplifiers are widely used to amplify optical signals, including Semiconductor Optical Amplifier (SOA) and more common amplifiers based on the Erbium-Doped Fiber Amplifier (EDFA).

Table: Sources of radiation used in telecommunications.
Note. Some lasers, including the VCSEL type, are listed with two classes at once since they exist in versions with different powers and for different applications. If in doubt, choose a more powerful Class 3 laser.

In North America, the main standard issued by the American Institute of Laser (Laser Institute of America) in 1988, which defines safety measures when working with optical cable systems, is ANSI Z136.2. (see “Classification of laser radiation sources according to their degree of danger to eyesight”).

Radiation detection.

Among the instruments used to detect radiation, the most common are optical power meters. They contain photodetectors, with the help of which the radiation power of various wavelengths is measured. In addition, other devices are also used - photosensor cards that respond to infrared radiation incident upon them with appropriate electronic activation, and infrared vision devices that convert infrared radiation with wavelengths of 800 and 1300 nm into visible light. Using the latter, the power characteristics of radiation sources are usually determined.

Specialists dealing with optical data transmission technology must be guided by the rule that any fiber can be active. Therefore, you should never look into the outlet of the transmitter or into the end of the connector.

For inspection of elements of optical cable systems, the most common instrument is a microscope. It is clear that it allows you to explore the surface of the fiber end, but is not able to detect the infrared radiation emanating from it. To control the quality of fiber surface treatment, microscopes with a magnification of 200-400 times are suitable. Usually, a laser filter is built into them to protect the eyes, attenuating the radiation level by 2–35 dB depending on the wavelength. Microscopes with filters are somewhat more expensive than conventional microscopes but safer. Always use precisely such microscopes in your work and, before ordering them, study the specification of each of them.
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Cheaper microscopes, with a magnification of 30-100 times, which are equipped with many kits for installing optical cable systems, often do not have filters at all. When working with them, the probability of accidental eye damage is high. Therefore, such devices are not recommended to be used either to control the quality of fiber processing or to verify compliance with safety requirements. In any case, when working with such a microscope, the user should always wear glasses that protect the eyes from laser radiation.

FOCL (fiber optic communication lines) details

The highest throughput among all existing means of communication has an optical fiber (dielectric waveguides). Fiber-optic cables are used to create fiber-optic communication lines - fiber-optic communication lines that can provide the highest speed of information transfer (depending on the type of active equipment used, the transmission speed can be tens of gigabytes or even terabytes per second).

In addition to the unique transmission characteristics, quartz glass, which is the FOCL carrier medium, has one more valuable property - low losses and insensitivity to electromagnetic fields. This sets it apart from conventional copper cable systems.

This information transfer system, as a rule, is used in the construction of working facilities as external highways, combining disparate structures or buildings, as well as multi-story buildings. It can also be used as an internal carrier of a structured cabling system (SCS), however, complete SCS made entirely of fiber are less common - due to the high cost of building optical communication lines.
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The use of FOCL allows locally combining jobs, ensuring high-speed Internet downloads simultaneously on all machines, high-quality telephone communications, and television reception.

Sections of the certified fiber optic technician course

It has a very important practical part that supposes approximately 70% of the time of the course. In the practical part, we work on fiber optic cables, connectors, splices, use test equipment and design a fiber-optic network as learned in the course. To begin each practical workshop, the teacher shows in great detail how the different techniques and methods are performed working with fiber optics and constantly monitors progress and teaches how to improve the technique.
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To obtain the official CFOT certification, participants must pass a final written exam. The exam is the test type with the book closed and consists of 100 questions. The minimum score is 70% correct answers. In addition, the skills and techniques of working with fiber optics in practical workshops must be demonstrated.

If you wish to attend the certified fiber optic technician course or receive more information, fill out and send the following contact form and we will send it to the course organizer immediately.

You can also find information on other technical courses and seminars in our Calendar of Technological Events or watch the recording of our Webinars.