What is an optical cable for the Internet. How does fiber optic cable work? Other applications of fiber

You can often see various advertisements about high-quality Internet and television. The signal acquires such properties as a result of moving to the consumer along lines of optical fibers, in which there is practically no information loss.

What is optical fiber

In an ordinary wire, an electrical signal travels through copper conductor. In optical lines, they pass light photons and waves. Optical fiber is considered the fastest way to transmit information over long distances. The cable consists of several individual conductors separated by special coatings. In the design, each individual element conducts information encrypted into the light.

The transmitted information can be used telephone and television data, as well as the Internet (thanks to fiber optics, they achieve high speed Internet access). Currently, all three signals for transmission are combined into one.

Constraint features

Over the past few years, the limits on data transmission rates in optical links have moved a lot forward. The speed depends on the length of the conductor, as well as the quality of the information itself. Single mode systems use the speed 2.5 Mbps to 10 Gbps at a transmission distance of 10 km or more. Research is currently underway that will soon make it possible to up to 160 Gbps. Do not forget that many cables are made multi-layered, which allows you to transfer much more information at high speed.

Advantages and disadvantages

Optical fibers in the process of operation by consumers, like any technical product, has its pros and cons. The advantages of this type of conductor include:

Anti-jamming. Any kind of electromagnetic influence is helpless in front of the optical fiber. Due to this property, they can be used near powerful radiation sources.
Does not conduct electricity, as a result of which the manufacturing of receiving and transmitting units is structurally facilitated.
Information security and compatibility electromagnetic impulses. Due to the susceptibility to any type of radiation, fiber optic cables do not emit electromagnetic waves during operation, as a result of which information is protected from interception.
Small attenuation. Thanks to the materials used, the signal does not lose its properties over long distances, thereby far surpassing its copper counterparts.
Increased throughput and bandwidth. Such abilities made it possible to transmit various types of signals in one optical cable, while they are mixed and do not interfere with each other.
Have low weight, and in some cases cost as opposed to electrical conductors.

The disadvantages include:

elevated personnel requirements during operation and maintenance;
low strength as a result of which cracks and breaks appear, the signal will begin to fade or be interrupted;
loss of connection when water enters the conductor.

Applicable materials

The following materials are used in fiber optic production:

quartz glass;
polymer-based materials.

quartz glass

Produced at melting the mineral quartz, which is a valuable breed. As a result of its application, optical fibers acquire the following positive properties:

Polymer materials

The use of such materials allows the use of optical fibers of great thickness, due to plasticity and stability in bending and bending. The disadvantage is inadmissibility of use in areas of infrared radiation, as a result of which signal attenuation occurs.

Device and principle of operation

Optical cables are a conductor consisting of several strands wrapped in a braided shield. The veins themselves made of glass or plastic and have increased smoothness for maximum conductivity.

The substance that carries information is light, it has the highest speed of movement. Cable cores- these are, in fact, glass tubes wrapped in metal foil, which serves as a screen that preserves the signal flow. Light passing through the cable is reflected from the walls and reaches the receiver. The speed of information transfer is lower than the speed of light, as a result of the fact that photons do not fly in a straight line.

The signal as a result of its movement is still suffers some losses. Attenuation largely depends on the quality of the materials used and the conditions for laying the fiber. The transmitter itself also plays an important role.

Varieties

In the modern version, optical fiber is divided into two main types, which differ in the size of the core:

single-mode;
multimode.

Singlemode

In this design, the core has a thickness of up to 8 microns. Due to the minimum dimensions, a single beam can pass through the fiber almost no loss. This type is used in lines over a considerable distance, where it is important to maintain signal quality.

Multimode

This type of core consists of fiber up to 62.5 microns thick. Multiple light beams are able to flow through such cables, allowing them to move simultaneously at different angles to the core. The signal in these wires experiencing significant losses as a result of many reflections from the shell.

Multimode optical fiber lines, in turn, are divided into two types:

gradient. In such cables, the density of the core changes at some places along the line, which allows the signal to reach a high speed in a shorter period of time.
Stepped. In this type of execution, the density of the core fibers is the same throughout the entire line.

Classification

According to the method of direct installation, optical cables are divided into the following types:

laying in the ground;
pipes for sewerage, as well as collectors;
underwater installation;
air lines.

Depending on the use and range of the transmitted signal, the optical fiber is divided into the following types:

when creating long lines over significant distances of a multichannel network, backbone cables, to ensure signal stability, the design uses fibers with a core up to 125 microns, at a wavelength of at least 1.55 microns;
when laying multichannel lines between regions and regions, zone wires, gradient fibers are used in their construction;
urban fiber they are laid along collectors and special channels, according to some characteristics they are similar to zone ones, the length of the line does not exceed 10 km;
pad field cables implies installation in various ways, both in the air and underground, is not subject to combustion, stretching, up to 12 fibers are used in the design;
submarine cable has a high resistance to stretching and tearing, does not pass moisture, has a reduced dispersion level;
object cables are used for installation inside specific isolated sections and channels, they do not use hydrophobic materials, which simplifies the laying process;
mounting wires are made in the form of a flat fiber bundle, they use gradient multimode optical fibers.

According to the version of the core of the optical cable, the following types are distinguished:

twisted concentric twist around one core;
center wire with the number of fibers up to 45;
curly core with the number of fibers up to 576;
flat design up to 288 fibers in it.

Connection methods

When laying a fiber optic cable, it is often necessary to use a variety of switching devices. When laying a line, the length of the wire in the bay is not always enough, and sometimes it is also necessary to branch a large wire into several small ones.

Currently, three main methods of switching this cable are used:

mechanical;
welding method;
use of splice.

It is worth noting that the fiber optic is not connected directly to the computer. If fiber optics is brought into the apartment to access the Internet, then in this case you need a special router with the ability to connect an optical fiber cable, or a special media converter that converts the optical signal.

The work on the connection is carried out in two stages:

a small piece of cable with a connector installed at the end welded to the end optical wire using an automatic welding machine;
subsequently installed connector connect with socket on the other end of the cable.

Switching by this method requires constant cleaning during operation. The signal loss in this case is great, manufacturers do not recommend using this method for outdoor mounting of optical lines.

A splice is a kind of construction, often a plastic block, inside which optical fibers of different cables are fixed. The connection process is performed according to the following scheme:

initially from isolation two endings cleared connected cables;
with the help of splice happens alignment of cleaned ends;
subsequently switching point carefully isolated.

This method implies less signal loss than mechanical. During operation, it is necessary to check the alignment of the centers of the spliced ends.

This method is considered the most reliable and allows the use of fiber optic wires spliced in this way for outdoor installation. Signal loss in this case is minimal. For welding, you will need a special automatic device.

And a dozen years ago and at the end of 2013, the optical fiber produced by the industry is standardized and has many types and subtypes. The main types of OV are discussed on the pages
Types and standards of optical fibers
Types of optical fibers

The most striking differences are the fibers multimode and singlemode.

The theory of transmission over them is discussed in the pages Modal Propagation in Fibers. Number of mods. Formula. Multi-mode stepped and smooth refractive index fibers

In appearance, optical fibers are no different. That is, without the appropriate devices, it is impossible to figure out which fiber has fallen into your hands. Appearance, color, and some properties of optical fibers are given by a special coating. Several sizes of OB have been standardized.

250 µm the same glass covered with lacquer insulation. Lacquer is usually used multi-colored and in addition to the insulating properties, the color of the fiber determines its conditional number in the module. (Color counting of fibers, identification by color in optical cables). Lacquer coating gives additional resistance to bending. This fiber is similar to fishing line and withstands bends with a radius of 5mm (see photo)

900 µm optical fiber in a buffered polymer coating. It is used in the manufacture of cords and the connection of fiber optic crosses. The color of the coating often determines the type of fiber. (Color count in fiber optic cables)

Optical fiber with lacquer (125 µm) and polymer (900 µm) coating,
at the bottom of the connector is closed with a cap (All photos)

Production of optical fibers and cables

The bulk of the fiber is produced by Fujikura (Japan) and Corning (USA). But more and more technological lines appear, including in Russia, producing one or another type of optical fiber. Some of the steps and principles of this process are described on the pages
Optical fiber production technology. Fabrication of preforms for fiber optics
Extraction of fiber from the preform

Further, optical fiber on special drums is delivered to cable factories, where it is used in the production of optical cables. Since cables for FOCL differ in purpose and method of laying, respectively, they have a different number of armor covers and differ in profile.

Marking of optical cables

There are many manufacturers of fiber optic cables in the CIS countries, and at the same time, each enterprise develops its own technical specifications (TS) for its products and marks it in its own way. Labeling systems are different and the following pages are devoted to the analysis of this problem.
Guide to marking and assigning fiber optic cables
List of possible fiber optic cable markings in alphabetical order
Fiber optic cable labeling sorted by manufacturer

Laying of fiber-optic communication lines (FOCL)

FOCLs are laid along overhead power lines, in the ground, cable ducts, along the walls of buildings and indoors. The laying of fiber optic cables over overhead power lines is covered in official documents:
Rules for the design, construction and operation of fiber-optic communication lines on overhead power lines with a voltage of 0.4-35 kV
Rules for the design, construction and operation of fiber-optic communication lines on overhead power lines with a voltage of 110 kV and above

Other types of laying almost do not differ from the methods of laying a cable with metal conductors and their features are described on the page from the "Manual for SLSMSS": Features of laying optical cables

Installation of couplings and terminal devices of FOCL

Enlarge photo

Fiber optic cables are similar in appearance to conventional cables. The whole complexity of "optics" is precisely in the connection of optical fibers to each other. It will not work to connect them "on the knee", for any type of OB connection, specialized tools and devices are required. Pages are devoted to methods of installation and measurements on optical fiber during the installation of sleeves, cross-countries and connectors.
FOCL terminals. Connectors
Fiber optic attenuators for FOCL
Fiber optic cleaver. Gel connectors for FOCL
Fiber optic welding. Types of welding machines
Description of the installation of fiber optic couplers and optical cross-connects

In the next photo, optical fibers are stacked in a fiber optic coupling cassette

Optical fiber in the sleeve cassette (Enlarge photo)

Fiber measurements

Measurements of optical fibers are made before laying (monitoring cable drums), during the installation of fiber optic couplings and crosses, and during the FOCL process. Measurements are carried out with two types of instruments: measurement with fiber optic testers and optical reflectometers (OTDR). Pages devoted to RH measurements
Types of FOCL measurements. Fiber measurements
Fiber optic cable (FOCL) measurements during installation

This topic is covered in more detail on the pages of the book Deciduous Reflectometry of Optical Fibers.
Loss measurement with optical testers
How OTDR works
Purpose of OTDR

Aging fiber optic (optical) cables

Documentation for FOCL

Installation of fiber optic couplings and cross-connects, as well as all measurements of optical cables, must be documented in the relevant protocols and passports. Below are links to pages of official rules and guidelines for the construction of communication lines.
Protocol for measuring the attenuation of optical fibers of building length, serial number "n" before laying (incoming control)

Fiber optic cable has become a standard component in most modern cable infrastructures. Its resistance to electromagnetic and radio frequency interference has made it one of the best for signal transmission. It is capable of transporting signals over considerable distances on most networks. Currently, fiber optic cable used on many residential streets and leads directly to houses. However, for many people, the very meaning of fiber, how it works and is still not very clear. In this article, we'll answer some of the most common questions about , help you choose one, and talk about when and how it should be used.

What is optical fiber?

Optical fiber, or optical glass, is essentially very thin threads of glass through which the light impulse is transmitted. Glass with a thin jacket is called a shell, a signal passes through it. These fiber optic strands are assembled together in a common jacket to form a cable. If you try to stretch the fiber strands during installation, you will most likely damage them. In some cable designs, you can see a solid core made of composite materials to give additional protection. To transmit a signal along glass filaments, electrical devices called optical transmitters convert electrical signals (electrons) into pulses of light (photons). The pulses are modulated so that the receiving end can interpret the received signal from the transmitting end. Once the signal is received, it is converted back from photons to electrons and then transmitted to the network. Usually an optical channel is required two fiber filaments, one for sending and one for receiving.

There are two types of optical fiber, multimode and single mode.

Multimode fiber allows the signal to pass in several modes along the inner surface of the glass thread or rod. The core of the fiber is available in diameters of 62.5 and 50 microns. A micrometer is 1 millionth of a meter. For comparison, human hair is about 100 microns in diameter. In multimode fiber, light is generated from an inexpensive light source, a light emitting diode. Digital watches use a similar technology. This LED-based optical transmitter is commonly referred to as a media converter. As the signal from the converter passes through the glass, it bounces back and forth along the inner wall of the shell until it reaches its destination. This process takes place in millions per second and provides data transfer rates of 10 Mbps or 100 Mbps. Slower LEDs are almost out of use now as the demand for large data bandwidth has increased. In order to achieve higher data transfer rates, the market has created a vertical cavity surface emitting laser. The VCSEL focuses the light into a narrower band in the glass and operates at higher speeds. The technology allows you to increase the transmission speed to 1 Gb / s and 10 Gb / s at low cost, using the appropriate fiber. The specially designed glass works better at higher data rates and allows signals to travel farther. For example, the best 50 µm fiber can accommodate 10 Gbps at distances up to 550 meters. single mode optical fiber usually has a core, 8.3 µm in diameter. Single-mode fiber requires laser technology to transmit and receive data. Although a laser is used, the light in a single-mode fiber is refracted from the fiber cladding. Single mode has the ability to transmit a signal for many kilometers, making it ideal for telephone and cable television. The electronics required to transmit a single-mode signal are much more expensive than multi-mode ones, so they are not often used in a local area network. Although the basic dimensions of multimode and single-mode fiber are different, both types of fibers have an outer diameter of about 250 µm. These cables are easier to work with.

Where is fiber optic cable used?

Fiber optic cables can carry more data over vast distances than conventional copper cables. Fiber used for communication networks buildings together, for example, linking a dormitory and a building on a university campus, and today they are used by a large number of residential consumers of television and telephone services. In most commercial buildings, fiber is used to connect the fixed MDF frame, where network servers are typically found, and telecom cabinets. For example, a small group of users may be located 500 meters from the MDF. An example, in fact, is the connection of all your computers to a network. So, standard communications are limited to 100 meters, they simply will not work at long distances. By placing network switches and including a media converter in the same housing, you can use fiber optic cable to cover those 100 meters. A data converter at the other end of the fiber optic cable completes the link. The fiber optic cable can be installed even in small spaces, as one optical cable can replace hundreds of copper communication cables.

Which optical fiber to choose, 50 microns or 62.5 microns?

Although 62.5 micron fiber was at its peak only a few years ago, 50 micron has quickly gained significant market share. 50um fiber can have 20 times greater throughput(data bandwidth) than 62.5 microns. For identification purposes, multimode and singlemode fiber are often separated by both performance levels and specific ISO/IEC standards that depend on bandwidth. The 62.5 µm multimode fiber is referred to as OM1. 50 micron fiber is called OM2, OM3 and recently OM4 has also appeared. As you can imagine, OM4 has more bandwidth than OM3 and OM3 has more bandwidth than OM2. Fifty micron OM3 fiber is rated for 10 Gbps of bandwidth up to 300 meters, while OM4 can transmit up to 550 meters. Thus, many users now prefer OM3 and OM4 over other glass types. Almost 80% of the 50 µm fiber is OM3 or OM4 fiber. If you need higher data rates or have a network upgrade plan, I recommend choosing OM3 or OM4.

What types of connectors should be used?

There are LC, FC, MT-RJ, ST and SC connectors. There are also MT/MTP types that can hold up to 12 strands of fiber and take up much less space than other connectors. Most Popular - ConnectorsSC type, also known as general purpose connectors, which must be pressed and turned to lock. Manufacturers prefer SC and ST connectors.

Which cable design to choose?

There are numerous designs of optical cables and almost any of them have a unique design. Closed or open cable with rigid buffer fibers is very popular if the installation requires the cable to leave the building for a short distance and then re-enter another enclosure. There are closed armored cables that can be used in industrial premises or places where the cable can be subjected to mechanical stress. This type of cable can save money because booking is an alternative metal pipe or plastic cable tunnel.

As you can see, when choosing an appropriate fiber optic cable design, you must carefully analyze all the cable paths and determine how much protection the strands of fiber need, how you want to place them indoors, and how you intend to hide them.

In the modern world, it is necessary to transfer information efficiently and quickly. Today, there is no more perfect and efficient way to transmit data than fiber optic cable. If someone thinks that this is a unique development, then he is deeply mistaken. The first optical fibers appeared at the end of the last century, and work is still underway to develop this technology.

To date, we already have a transmitting material that is unique in its properties. Its use has gained wide popularity. Information in our time is of great importance. With the help of it, we communicate, develop the economy and life. At the same time, the speed of information transfer must be high in order to ensure the necessary pace of modern life. Therefore, now many Internet providers are introducing fiber optic cable.

This type of conductor is intended only for the transmission of a pulse of light that carries part of the information. Therefore, it is used to transmit informative data, and not to connect power. Fiber optic cable makes it possible to increase the speed several times, in comparison with metal wires. During operation, it has no side effects, deterioration in quality at a distance, overheating of the wire. The advantage of a cable based on optical fibers is the impossibility of influencing the transmitted signal, so it does not need a screen, stray currents do not affect it.

Classification

Fiber optic cable differs greatly from twisted pair cable in terms of application and installation location. There are main types of cables based on optical fiber:

For indoor installation.
Installations in cable channels, without armor.
Installations in cable channels, armored.
Ground laying.
Suspended, without a cable.
Suspended, with rope.
For underwater installation.

Device

The simplest device has a fiber optic cable for indoor installation, as well as a cable of a conventional design that does not have armor. The most complex design is for cables for underwater installation and for installation in the ground.

Indoor cable

Internal cables are divided into subscriber cables, for laying to the consumer, and distribution cables for creating a network. Optics are carried out in cable channels, trays. Some varieties are laid along the facade of the building to the switch box, or to the subscriber himself.

The fiber optic device for indoor laying consists of an optical fiber, a special protective coating, power elements, such as a cable. Fire safety requirements are imposed on the cable laid inside buildings: resistance to burning, low smoke emission. The cable sheath material is polyurethane, not polyethylene. The cable should be light, thin and flexible. Many versions of fiber optic cable are lightweight and protected from moisture.

Indoors, the cable is usually laid over short distances, so there is no talk of signal attenuation and the impact on information transmission. In such cables, the number of optical fibers is not more than twelve. There are also hybrid fiber optic cables that contain twisted pair.

Cable without armor for cable ducts

Optics without armor is used for installation in cable ducts, provided that there is no mechanical impact from the outside. This version of the cable is used for tunnels and collectors of houses. It is laid in polyethylene pipes, manually or with a special winch. A feature of this version of the cable is the presence of a hydrophobic filler, which guarantees normal operation in the cable channel, protects against moisture.

Armored cable for cable ducts

An armored fiber optic cable is used when there are loads from the outside, for example, tensile. Armor is done differently. Armor in the form of a tape is used if there is no exposure to aggressive substances, in tunnels, etc. The armor structure consists of a steel pipe (corrugated or smooth), with a wall thickness of 0.25 mm. Corrugation is performed when it is one layer of cable protection. It protects the optical fiber from rodents, increases the flexibility of the cable. Under conditions with a high risk of damage, wire armor is used, for example, at the bottom of a river, or in the ground.

Cable for laying in the ground

To install the cable into the ground, an optical fiber with wire armor is used. Reinforced tape-armoured cables can also be used, but they are not widely used. To lay the fiber in the ground, a cable layer is used. If installation in the ground is carried out in cold weather at a temperature of less than -10 degrees, then the cable is heated in advance.

For wet ground, a cable with a sealed optical fiber in a metal tube is used, and the wire armor is impregnated with a water-repellent composition. Experts make calculations for laying the cable. They determine the permissible stretching, compression loads, etc. Otherwise, after a certain time, the optical fibers will be damaged and the cable will become unusable.

Armor has an effect on the value of the allowable tensile load. Optical fiber with wire armor withstands a load of up to 80 kN, with tape armor, the load can be no more than 2.7 kN.

Overhead fiber optic cable without armor

Such cables are installed on the supports of communication and power lines. So installation is easier and more convenient than in the ground. At the same time, there is an important limitation - during installation, the temperature should not fall below -15 degrees. The cross section of the cable is round. This reduces wind loads on the cable. The distance between supports should be no more than 100 meters. The design has a strength element in the form of fiberglass.

Thanks to the strength element, the cable can withstand heavy loads directed along it. Strength elements in the form of aramid threads are used at distances between poles up to 1000 meters. The advantage of aramid threads, in addition to low weight and strength, is the dielectric properties of aramid. If lightning strikes the cable, there will be no damage.

The cores of overhead cables are different. According to their type, cables are divided into:

Profile core cable, fiber optic is crush and stretch resistant.
Cable with twisted type modules, optical fibers are laid freely, there is resistance to stretching.
With an optical module, the core has nothing other than optical fiber. The disadvantage of this design is that it is inconvenient to identify the fibers. Advantage - small diameter, low cost.

Optical fiber cable with tether

Cable fiber is self-supporting. Such cables are used for laying through the air. The cable is either load-bearing or winding. There are cable models in which the optical fiber is inside the lightning protection cable. The cable, reinforced with a profile core, has sufficient efficiency. The cable consists of a steel wire in a sheath. This sheath is connected to the cable sheath. The free volume is filled with a hydrophobic substance. Such cables are laid with a distance between the poles of not more than 70 meters. The limitation of the cable is the impossibility of laying on the power line.

Cables with a lightning protection cable are installed on high-voltage lines with fixation to ground. Rope cable is used at the risk of damage by animals, or over long distances.

Underwater fiber optic cable

This type of optical fiber is isolated from the rest, because its laying takes place in special conditions. All submarine cables have armor, the design of which depends on the depth of laying and the topography of the bottom of the reservoir.

Some types of underwater optical fiber for the execution of armor with:

Single armor.
Reinforced armor.
Reinforced double armor.
Without armor.

1› Polyethylene insulation.
2› Mylar coated.
3› Double wire armor.
4› Aluminum waterproofing.
5› Polycarbonate.
6› Central tube.
7› The filler is hydrophobic.
8› Optical fiber.

The size of the armor does not depend on the depth of the lining. Reinforcement protects the cable only from the inhabitants of the reservoir, anchors, ships.

Fiber splicing

For welding, a special type of welding machine is used. It contains a microscope, clamps for fixing fibers, arc welding, a heat shrink chamber for heating sleeves, a microprocessor for control and monitoring.

Brief technical process of fiber optic splicing:

Removing the shell with a stripper.
Preparation for welding. Sleeves are put on the ends. The ends of the fibers are degreased with alcohol. The end of the fiber is cleaved with a special device at a certain angle. The fibers are placed in the apparatus.
Welding. The fibers are aligned. With automatic control, the position of the fibers is set automatically. After confirmation by the welder, the fibers are welded by the machine. With manual control, all operations are carried out manually by a specialist. When welding, the fibers are melted by an electric arc, combined. Then the place to be welded is heated to avoid internal stresses.
Quality checking. The automatic welding machine analyzes the image of the welding place under a microscope, determines the assessment of the work. An accurate result is obtained by a reflectometer, which detects inhomogeneity and attenuation in the welding line.
Processing and protection of the welded area. The put on sleeve is shifted for welding and placed in the oven for heat shrinking for one minute. After that, the sleeve cools down, lies down in the protective plate of the coupling, and a spare optical fiber is superimposed.

Advantages of fiber optic cable

The main advantage of optical fiber is the increased speed of information transfer, there is practically no signal attenuation (very low), as well as the security of data transmission.

It is impossible to connect to the optical line without sanctions. Any connection to the network will damage the optical fibers.
Electrical safety. It increases the popularity and scope of such cables. They are increasingly being used in industry for the danger of explosions in production.
It has good protection against interference of natural origin, electrical equipment, etc.

And the Internet over fiber optic cable is the latest change in the way data is transmitted around the world. It is much faster than a regular cable, faster than dial-up, and can carry large amounts of data, often reaching several terabytes of data transfer quite easily.

To fiber: DSL and cable

Digital Subscriber Line (DSL) used existing telephone data lines, which were usually made of copper. DSL is slow, old, and mostly phased out in favor of cable, but it remains in some rural areas. The average speed for DSL is about 2 Mbps.

Cable Internet uses coaxial cable, also made of copper, and usually comes with the same cables used to control a TV network. That's why many ISPs offer bundled plans with a TV subscription and Internet access. The average speed for cable varies, but ranges from 20 Mbps to 100 Mbps.

Optical fiber

Fiber optic cables use small glass fibers to transmit data using pulses of light. Light travels the same way electricity travels through copper wire, but the advantage is that fiber cables can carry multiple signals at the same time. They are incredibly small, which is why they are often bundled into larger cables called "fiber optic trunk cables", each containing several fiber links. Fiber cables carry a huge amount of data, and the average speed you'll see in your home is around 1 Gbps (often referred to as "gigabit internet").

Fiber backbones form the bulk of today's Internet, and you'll see their benefits even if you don't have a "fiber Internet". This is because Internet Exchange Points (IXPs)—the switching and routing stations that connect your home to the rest of the world—use fiber optic backbones to connect to other IXPs.

But when it comes time to connect all the houses in the city to your local IXP (a term commonly referred to as "last mile"), your ISP will usually use traditional coaxial cable for your home. This option becomes the bottleneck for your internet speed. When someone says they have "fiber internet", what they mean is that the connection from their home to the IXP also uses fiber, minus the copper cable speed limit.

Fiber limits

There is a reason why fiber optic internet is not publicly available. Fiber is much more expensive to run and does not justify the cost when cable lines are often already available. For most people, the 20-100 Mbps they get on cable is sufficient, as most Internet downloads won't exceed this connection anyway.

And while fiber is certainly better than copper, you won't see an increase in actual download speed due to limitations on the server you're downloading from. An app like Steam downloading a 10GB game will only seem to take a few seconds on a 1000Mbps fiber connection, but you'll actually get a maximum of 50Mbps from the Steam servers.