Design , features and characteristics of the optical cable

Progress does not stop.Every day in our lives includes all new material.Breakthroughs in terms of laying the high-speed communications was the invention of the optical cable.

What is optical cable

Optical Cable is a special kind of cable for communications networks.The main difference from the standard cable - power transmission method.Transmitted using the light flux rather than electric current.By and large optic cable - a thread, within which the movement of light occurs.The main component - optical fiber.It is the most modern and most reliable medium for data transmission.The light is transmitted by fiber over long distances with little or no loss and with great speed.

main characteristics of optical cable.Its advantages and disadvantages

optic advantage over conventional cable surely.Among the most obvious points I would like to highlight:

• Incredibly high throughput.The optical cable able to transmit large amounts of information for a small period of time.
• fiber does not radiate electromagnetic waves.Accordingly, it is not able to be exposed to electromagnetic radiation.As a result, the signal is protected from distortion.
• cable is securely protected from unauthorized connections.Attempt unauthorized connection disturbs the integrity of the cable and the termination of data transmission.Hide it becomes impossible.
• very minor component of the signal attenuation.Modern optical fiber cable at a wavelength of 1500 nm has an index of attenuation of about 0.3 dB / km.This makes it possible to arrange adjacent repeaters and amplifiers at a distance of 100 km.
• optical cable has a lower weight and volume than normal.For example, a diameter of 900-pair telephone cable 7.5 cm. It successfully replaces the optical cable with a diameter of about 1.5 cm. In this case, most of the cables will make all sorts of protective shell.The diameter of the fiber itself is 0.1 cm.

• no need to shell grounding When using an optical cable.This is due to the insulating properties of the fiber.
• Can be used on a high-risk ventures.Associated with this feature of the fiber as the absence of sparking.It is thanks to her optic cable - fireproof material.
• Optical Cable - very economical material.Quartz is used for the manufacture of optical fiber, the element is very inexpensive and abundant.As a result, the cost of the optical cable does not differ from the value of a physical cable.
• durability.Nothing is eternal.Over time lose their properties of all materials, including fiber optic cable.Increases attenuation.However, these processes take place very slowly.Speed ​​loss properties of optical cable is considerably lower compared with other types of cables.The term of the smooth operation of the optical cable is not less than 25 years.

Despite the large number of positive aspects, the use of fiber optic cable has a number of drawbacks:

• high cost of communication with the optical cable.However, this is due to the use of additional expensive equipment.The cost of the optical cable is not too different from the cost of a conventional cable.The complexity of networks
• mount with an optical cable.Connectors should be installed just with micron accuracy.The connection itself must be carried out very precisely, exactly.The presence of the gaps is not allowed.The interface must be polished smooth.If the above requirements are not avoid losses in speed and quality of the transmitted signal.
• Connections are made by welding or gluing.When gluing, a special gel is used having the same value of refractive index as that of glass fibers.
• In operation, the optical cable used special tools.Installation of optical networks is carried out exclusively by qualified personnel.
• possible damage of the optical cable due to extreme temperatures.The glass cracked.To solve this problem in the production of running optical cables in the manufacturing process which uses a radiation-resistant glass.Unfortunately, this leads to a significant increase in cost.

As you can see, the shortcomings were not significant.optical networks are growing in popularity with each passing day.At the same time it reduces material costs and a growing number of professionals working with optical cable.If such a trend these shortcomings izzhivut itself in the near future.

types of optical cables

There are two types of optical cables:

1. single-mode fiber optic cable.All the light rays in the cables of this type are moving along the same path and at the same time suitable to the receiver.As a result, no waveform distortion.Single-mode fiber optic cable has a diameter of 1,300 nm.Transmits only light waves of the same length.Using single-mode cables contributes to signal transmission over longer distances than the use of multimode cables.This feature is due to very small values ​​of signal loss and dispersion.When using single-mode cables are used laser LEDs.signal attenuation in the single cable is very low, of the order of 5 dB / km.
2. multimode fiber optic cable.In this type of cable-rays do not go along the same path.Their trajectories are different and have varying.Result - signal distortion at the receiver.When transmitting a signal conventional LEDs used for multimode cable.This leads to a significant reduction in the cost of communications networks and services increase in terms of transceivers.For multimode fiber characteristic light wavelength of about 850 nm with deviations of 30-50 nm.Attenuation in the cable can be up to 20 dB / km.Allowed this type of cable length up to 5 km.

main type of optical cable is now a multi-mode.This is due to its availability and cheapness.In the future, a leader must move to single-mode cable.Its excellent performance, low attenuation levels allow us to hope that in time the high cost of transmitting and receiving equipment will no longer be an obstacle to the spread of high-quality material.

design of optical cable

The main components of the optical cable are:

1. optical fiber.Thin glass yarn called core or core.Coated glass.cladding refractive index is slightly different from the same core index downwards.That is why the light beam directed to the core only extends over it.Often, to reduce the cost of core material is made of plastic instead of glass.Such optical fibers worse.There are single-mode and multimode optical fiber.Core single-mode fiber is very thin, its diameter is about 10 microns.It is due to the small diameter of the core is transmitted by only one single mode of the electromagnetic radiation, which excludes the presence of dispersion distortions.But the multimode fiber core is several times thicker than about 50 microns.This contributes to the spread on it a few radiation modes.Each of the modes is distributed under a certain angle.A light pulse is subject to dispersion, which leads to the transformation of its shape of a rectangular bell-in.
2. core.

To improve the strength of the fiber optic cable and its optical modules, is a polymer tube in which freely movable optical fiber, twisted around the core of the cable.

core role performs the central power element that protects the structure from loads.

In the production of optical cables used stranding layers.Elements twisted concentrically arranged along a central strength member.The objective lay - to achieve the presence of the space within which to transfer the cable does not affect the ability of the compressive load, tensile and flexural strength.Of course, the maximum value of the load is limited in scope.

around the central strength member are wound and fillers.As fillers act:

1. modules without fiber.
2. Copper wires
3. plastic rods.

All these elements are bonded to each other tape or coating.They are collectively called the core.

1. Covers for protection and reinforcement.In the absence of the need for shielding the optical cable from external electromagnetic barriers of metal braid is not applicable.However, there arises the need for mechanical protection of the cable.For this purpose, use the following materials:

• Kevlar;
• ribbon of steel;
• steel wire.

2. The outer sheath.It protects the cable from external influences both mechanical and noxious substances effects of moisture.

Variety designs

cable constructions are the following varieties:

• cable for outdoor installation.Purpose - laying in the ground or in a pipe.

Scope odnosvetovodnyh- cables with the presence of Nemea 10 fibers.But when more fiber is better to use a resin impregnated mnogosvetovodny module module.

modules entwine layers along the central strength member.

Force elements with a coating of polyethylene or laminated sheath made of polyethylene, laminated with aluminum.

module is filled with hydrophobic compound.

the possibility of imposing additional shell layer of protective armor.In order to protect against pests perfect strip of corrugated steel.

• cable for internal wiring.It is used inside buildings.grounding is not necessary, since they do not contain metal cables for this species.Easy to use due to the ease and flexibility.

Distinguish cables:

1. Distribution.For individual wiring.Three kinds of designs based on the module diameter:

• under severe conditions of use - 0.27 cm;
• under standard conditions of use - 0.24 cm;
• in alleviating the conditions of application -. 0.20 cm

laid in vertical shafts in buildings or in channels located below the level of freezing, between adjacent buildings.

2. Connection.Used as jumper cables or in the process of terminating plug connectors.

3. Special cable.This universal cables used and the outside and inside.Features of this type of optical cable:

• complete water resistance;
• no need for additional splice at the entrance to the building;
• presence of special fire requirements.

Varieties of special cables are undersea cable and the optical self-supporting, also called air.

Air cable laid along the poles.This may be the pillars of lighting and communications, power lines, electric networks.Options overhead cables the device very much.It all depends on the model.A characteristic feature of the aerial cable is a high tensile strength.After the load on it is not limited to its own weight.There is an increase in load due to icing, wind.

Submarine cables lay in deep water.Central tube cables of this type are made from copper and filled with hydrophobic gel.Here are the armor layer 2-3 wire galvanized steel.Between the layers, and the outside layer is polyethylene.As a result, the cable feels great in deep water and can withstand considerable pressure