Fiber optic cables: structure and types available (2023)

Fiber optic cables: structure and types available (1)

The world of telecommunications is rapidly changing from copper wire networks to fiber optic networks. WhileCoax kabelWe use it with cell phone signal booster kits (aka "Passive distributed antenna system) is still the norm because they perform very well in these conditions, fiber technology is a decisive factor when usedActive distributed antenna system(Active DAS). Fiber optic cables fundamentally change telecommunications and connectivity. Today, signals can easily be sent around the globe at the speed of light using fiber optic cables.

What is fiber optic cable and what is it used for?

A fiber optic cable is essentially a network cable: a cable in which fiber optics are contained in an insulated housing. Fiber optic cables are specially designed to transmit high-performance telecommunications and data networks over long distances.

Fiber optic cables consist of one or more strands of glass about the thickness of a human hair surrounded by an insulated outer jacket. They offer higher bandwidth than wireless coaxial cables and can transport data over longer distances. These cables are responsible for supporting most telephone systems, cable television and the Internet in the world.

The fiber optic cable transmits communication signals using light pulses generated by light emitting diodes or small lasers. At the center of each glass strand is the "core," and the core is surrounded by a cladding, a layer of glass that reflects light inward, allowing light to pass through bends in the cable while preventing signal loss. It is the core of the cable that allows the light to travel long distances. Unlike electrical signals, fiber optic cables use light pulses to transmit information.

How do we use fiber optic cable?

The world of network communications has been completely revolutionized by fiber optic cables since their inception nearly 40 years ago. Some of the more obvious uses of fiber optic cables are listed below:

The InternetBecause fiber optic cables are capable of transmitting huge amounts of data at high speed. Compared to traditional copper wire, fiber optic cable is more flexible, lighter, less bulky and can carry more data.

Telephone, because using fiber optic communication means faster connections and clearer conversations without delays on both sides.

cable TV, as fiber optic cables have higher speeds and bandwidths, making them perfect for carrying signals for high-definition television. In addition, the same amount of fiber optic cable is significantly cheaper compared to copper wire.

dentistry and surgery, including microscopic and biomedical research. Fiber optic cables are widely used in medicine and research. Non-invasive surgical methods, also called endoscopy, require optical communication. It uses a small, bright light to illuminate the surgical area inside the body. This makes it possible to reduce both the size and the number of cuts.

computer network, because the use of fiber optic cables makes networking much easier and faster. Users report that the time it takes to transfer information and files across networks is drastically reduced when using fiber optic cables.

car industry, where fiber optic cables play a very important safety role in today's modern vehicles. These cables are commonly used for exterior and interior vehicle lighting. And fiber optic cables become invaluable when using safety applications like airbags and traction control. The reason for this is that signals can be transmitted between different parts of the vehicle at lightning speed.

lighting and decorations, because fiber optic cables offer an economical, simple and attractive solution for lighting projects such as Christmas trees and other light decorations.

Space and military applications, because both the aerospace and military sectors require an extremely high level of data security, and fiber optic cables offer the ideal solution for data transmission.

Mechanical inspections, which uses fiber optic cables to inspect hard-to-reach places. This may include plumbers inspecting pipes and on-site inspections by engineers.

Who uses fiber optic cable?

To create a physical connection to a device or network, fiber optic cables can be easily connected to patch panels and communication devices. They are only used by usActive Distributed Antenne Systems (Active DAS). The fiber optic distribution network that connects wireless carrier signal lines to antennas and other equipmenttransmits cellular signals most efficiently. Fiber optic cables are typically used by governments, commercial companies, and the military, and of course there are many other industrial applications that use fiber optic cables to transmit data, video, and voice.

Frequently used fiber optic terms:

Absorption: The absorption of light energy in an optical fiber during transmission caused by natural impurities in the glass. The main cause of signal loss (attenuation) in an optical fiber is absorption and scattering. See below for "Scatter".

attenuation: Attenuation caused by absorption and scattering is the loss of signal strength or signal strength during transmission as it travels along a fiber between two points. Attenuation is usually measured per length unit and expressed in dB per kilometer.

speechless: A device that introduces loss to reduce signal power in a fiber optic link.

from behind: BR (back reflection) typically occurs at connector interfaces where reflection is caused by a glass-air interface. BR is a term used for any process that causes light in a fiber to change direction and return to the source.

bandwidth: This is the highest frequency that can be transmitted by an analog system. Bandwidth is also the information transfer capacity in digital systems. This is the range of frequencies that a terminal device or fiber optic cable can transmit information or data. Because distance matters, bandwidth is measured in MHz-km and GHz-km.

Puffer: Buffer is a protective layer applied directly to the fiber to protect the fiber or cable from physical damage. Fabrication techniques include loose tube buffering, tight casing buffering and may also include multiple buffer layers.

insertion loss: When a component such as a splice or connection point is inserted into a fiber optic system, the loss it causes is called the total optical power loss.

loss budget: The maximum power loss per optical connection. Loss budget can be described as the maximum loss tolerated by a given link.

Multimode: A fiber optic cable whose core diameter is much larger than the singlemode waveguide core – 50µm+ compared to 2µm to 9µm, therefore multimode fiber is used instead of singlemode fiber for short runs. Multimode is an optical fiber that transmits multiple modes of light.

loss of return: (Optical Return Loss) expressed in dB units. Optical return loss is the ratio of the power injected into a cable to the optical power returned down the fiber. Expressed in positive dB values, it is better to have a higher value.

spread: Diffusion is one of the main causes of attenuation. It occurs when light changes direction after colliding with small particles, causing loss in the optical fibers.

single player mode: An optical fiber (or waveguide) with a small core diameter; The signal travels a path through its core. Used for high-speed transmission over long distances, its smaller core makes it difficult to couple the light source. However, it offers a wider bandwidth than multimode. Single-mode optical fibers typically have an 8-10 µm thick core within a 125 µm thick cladding.

wavelength: Wavelength is expressed in microns or nanometers and is a measure of the color of light. Measurements are taken from a point on one wave to the corresponding point on the next wave. The wavelengths are typically 850, 1300 and 1350 nm.

Multimode Cable vs. Singlemode Cable.

Multimode cables are typically available in two core sizes: 50 µm and 62.5 µm. The core has a large diameter and several light paths. This cable is generally used for voice and data fiber applications, e.g. B. as a supplement to existing networks, but also for applications such as fiber optic transmission for desktop and alarm systems. Both core sizes of multimode cable use either laser light sources or LEDs.

For new installations and constructions, a multimode 50 µm cable should be considered as it provides higher speeds and longer link lengths at the 850 nm wavelength than the 62.5 µm cable. This type of cable is recommended for indoor applications, e.g. B. for intra-building, horizontal and backbone connections.

While single-mode cables have a yellow sheath, multimode cables typically have a teal or orange sheath. Additional colors are available for identification for a variety of applications.

Since single-mode cables have a smaller glass core of 8 to 10 µm, there is only one passage for light. This means that the light is directed towards the center of the core, as opposed to multimode, where the light is reflected from the edge of the core.

Compared to multimode cables, singlemode cable is able to provide 50 times longer distance. This means that single-mode cables are preferred for high-bandwidth applications as well as long-distance, long-range network connections. This includes campus backbone applications and cable television. Because singlemode cable offers higher bandwidth, singlemode fiber strands can be used in full-duplex mode with more than twice the throughput of multimode fiber.

Construction of fiber optic cables.

A fiber optic cable serves to protect the inner core of the fiber which carries the transmission of a light signal. The construction of a fiber optic cable includes the fiber core, the cladding, the primary coating, strength elements (or buffer reinforcement fibers) and the cable jacket.

Kern: The fiber core in a fiber optic cable is the central physical medium of the cable, which transmits the light signal received from a connected light source and relays it to a receiving device. This core is a continuous hair-thin strand of fused silica or plastic, measured by the size of its outside diameter. While single-mode cores are typically less than 9 µm, the most commonly available multi-mode fiber cable sizes are 50 µm and 62.5 µm.

disguise: The cladding is a thin layer of glass that surrounds the fiber core, forming a single solid glass fiber used for light transmission. It creates a boundary that restricts the light waves, resulting in refraction. This allows data to be transmitted over the entire length of the fiber segment.

primary coating: The primary coating comes after the cladding and is also known as the primary buffer. It is designed to absorb shock, provide protection against excessive cable bending and reinforce the fiber core. This primary coating is essentially a plastic layer that does not affect the cladding or the light transmission of the core. These coatings are measured in microns - the buffer is 900 µm and the coating is 250 µm.

Strengthen members: Also known as reinforcing fibers. These are strands of Kevlar (aramid yarn) specially placed to protect the core from excessive tension during installation and other crushing forces.

cable cap: The outermost layer of a cable is called the cable jacket. Depending on the application, some fiber optic cables have yellow, black, aquamarine, or other colored jackets. However, fiber optic cables typically have an orange sheath. Within a network, different applications can be identified by different colors.

Cable differences:

Comparison of simplex cables and duplex patch cables.

A simplex fiber optic cable consists of a single strand of plastic or fiber optics. It is typically used when a multiplexed data signal is used or when only one transmit and/or receive line is needed between devices. On the other hand, a duplex zippered fiber optic cable consists of two strands of plastic or fiberglass bonded by a thin fabric and is typically used where separate transmit and receive functions are required for duplex communication between devices.

Both multimode and singlemode patch cords can be either duplex or simplex, and both duplex zipcord and simplex are densely buffered and covered with Kevlar reinforcing fibers.

Because simplex fiber optic cable has only one fiber optic connection, it should be used for applications that require one-way data transmission. For example, an oil line monitor sends oil flow data to a central office, or an interstate truck scale, which sends a truck's weight to a monitoring station.

For applications that require simultaneous, bidirectional data transmission, singlemode fiber optic cables and duplex multimode cables should be used. Duplex cables are required for hardware applications such as workstations, Ethernet switches, fiber optic switches and servers and backbone ports.

Comparison of PVC cables (riser) and plenum cables

Over the years, PVC cable has become synonymous with riser cable. However, this is not always completely correct. Risers are a subset of PVC cables, and not all PVC cables are designed for risers. Therefore, caution should be exercised in using these two terms interchangeably. PVC cables are characterized by their outer sheath made of polyvinyl chloride, which emits particularly toxic fumes in case of fire or even overheating.

A riser-rated cable has a fireproof jacket, but will still emit toxic fumes if ignited.

Provided that the building's ventilation system is fully functional, PVC cables can be suitable for both vertical and horizontal ducts.Executive kabelcan be used as a substitute for PVC. However, the opposite is not true: that is, PVC cannot be used in plenum rooms.

A plenum in a building is designed to allow ambient air to move freely. For example, in an office space, an area above the heating, ventilation, and air conditioning (HVAC) system on the outside of the ceiling is typically a plenum. Any cable installed in a plenum must be plenum-rated, meaning its jacket is made of this material. For example, Teflon emits significantly less toxic fumes than PVC cable when ignited.

PVC cables are classified as Optical Fiber Nonconductive Risers (OFNR) and are unsuitable for use in plenums. OFNR is generally intended for vertical runs between floors as part of a fiber optic backbone. This type of cable meets the Underwriters Laboratories (UL) Riser/1666 fire rating test. On the other hand, the non-conductive optical fiber plenum (OFNP) is generally intended for horizontal ducts, especially inside a ventilation duct. This type of cable meets the Underwriters Laboratories (UL) Plenum/910 fire rating test.

Comparison of distribution cables and breakout cables.

In general, relatively small distribution cables are made up of fibers tightly bound together in the same jacket. They are then coated and reinforced with fiberglass or Kevlar. Suitable for both dry and short cable runs. Distribution-style cables can be used in both headers and risers. Although it is possible to terminate fibers directly in a distribution line, it is important to note that the fibers in the bundle are not individually reinforced and must therefore be terminated in a cabinet, fiber optic enclosure, junction box or patch panel.

Breakout cables, on the other hand, are larger and more stable than splitter cables. Breakout cables are suitable for both plenum and riser and consist of a bundle of individual simplex cables.

Comparison of loose tube cables and tight tube cables.

Both close-fitting and loose tube cables are reinforced in some way, e.g. with stranded wire made of stainless steel or aramid yarn. However, this is where the similarities end, as each is designed for use in wildly different spaces.

Loose tube cables are suitable for outdoor use and are designed to withstand harsh weather conditions, including areas with high humidity. Semi-rigid tubes or protective sleeves protect the cladding, fiber core and cladding, and the fibers themselves are also protected from moisture by a water-repellent gel. Because gel-filled loose tube cables contract and expand with temperature changes, they protect against condensation and water, but are not the ideal choice for indoor use.

Long indoor runs or medium LAN/WAN runs are best suited for a narrow-gauge cable, which is more robust than loose tube cables. Because no internal gel or fanout kit is required for termination or splicing, tight tube cables are easier to install indoors than loose tube cables.

Indoor/outdoor dual use cable.

With dry-block technology to protect against moisture leakage and gel-filled buffer tubing to prevent moisture migration, indoor/outdoor cables are perfect for riser, sump, duck and plenum applications. The indoor/outdoor cable is housed in an outer jacket with an aramid yarn covering and a flame retardant layer to protect the core binder and ripcord.

Interlocking armored cable.

The interlocking armored cable can be used almost anywhere. The interlocking, armored cable is built to withstand rodents and harsh conditions. It is robust and has a reinforced aluminum jacket that can lock together for extra protection. No wire is required for interlocking armored cables. This saves you money and installation time compared to running fiber optic cables through internal ducts.

For direct burial, a cable outside the system is the ideal solution. The rodent and waterproof outdoor cable is designed to withstand extreme weather conditions and terminates within 50 feet of the building entrance.

Flexible and lightweight, the interlocking armored cable is surprisingly strong and is often the best choice for building connections that are off the beaten path.

Laser optimized 10 Gigabit cable.

The laser optimized 10 Gigabit cable is ideal for building long distance network applications and is typically aqua colored. This type of cable assembly differs from typical multimode cable assemblies in one important respect. Laser-optimized joints include a fiber optic cable with a refractive index profile that is graded within each joint. This lowers the refractive index of the core glass towards the outer cladding, meaning light travels faster towards the outside of the fiber than in other directions. This equalizes the transit time of long and short light paths, which significantly increases the accuracy of transmission and reception of information over long distances, up to 300 meters at a speed of 10 Gbit/s.

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