ClearCurve

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ClearCurve is Corning's brand name for a new optical fiber that can be bent around short-radius curves without losing its signal. It is constructed with a conventional fiber on the inside, surrounded by a cladding containing a new nanostructured reflector. ClearCurve is hundreds of times more flexible than conventional optical cable, transmitting high-quality signals even when wrapped around small objects like a pen, where a conventional cable would lose the signal completely.

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Although originally introduced to serve the needs of pulling fiber in apartment buildings and other high-density units where conventional fiber is too inflexible, in 2009 Intel announced their intention to use it as the basis of a new computer interconnect system code-named Light Peak. ClearCurve's small size and high bandwidth capabilities offer great improvements over existing copper wiring in this role, and Intel is positioning Light Peak as a truly universal bus that can carry any existing traffic over a single cable.

Background

Conventional fiber

Conventional single-mode long-haul optical fiber cable. Optical fiber cable.jpg
Conventional single-mode long-haul optical fiber cable.

Conventional optical fiber consists of a thin inner cylindrical core of glass or plastic with a similar material layered in a thin coating around it. Slight differences in the index of refraction between the two layers causes total internal reflection, trapping a light beam inside the inner core. This process is limited to a critical angle; when the light beam approaches the interface at a shallow angle most of it will be reflected, but as it gets closer to the critical angle more and more will travel through the interface and be lost. [1]

The critical angle depends on the relative difference in index of refraction, larger differences will increase the critical angle and trap more light. However, changing the index of refraction in most materials generally changes its mechanical properties too, which means that different types of cables are used for different purposes. Cables intended to be highly efficient over long runs are generally less flexible, while those that require higher flexibility are generally only useful for shorter distances. Even cables designed to be flexible, like TOSLINK, are less flexible than a similar sized braided copper cable.

To keep the fibers as straight as possible, most high-performance optical cables use a form of armour that resists tight bending. This is normally a helical winding, similar to BX cable, or a series of straight fibers running parallel to the core. [2] Since the armour is fairly large, the cables normally carry a number of fibers inside. The resulting armoured bundle is then surrounded in an environmental cladding, typically plastic. The bundle is about the size of a conventional power cable found on an electrical appliance, but much less flexible.

Fiber to the home

Optical cabling has long formed the backbone of major terrestrial networks, delivering signals over long distances. The signals are then converted into other forms at the company end offices, and distributed from there in some other form, typically telephone wiring or coax cable in the case of cable television. The multi-fiber armoured cable is well suited to this role.

Since the 1990s there has been an ongoing effort to supply fiber to the home (FTTH). Using fiber to deliver signals all the way to the home provides the same advantages as it does on the longer hauls, namely much higher bandwidth, lower costs, and less interference with other sources. However, given the deliberate lack of flexibility of the cable, these installations generally end in a utility room where they are converted to copper for distribution within the home. [3]

While this sort of installation is useful for individual dwellings, it is less useful in large multi-unit dwellings. Corning estimates that an apartment installation would require an average of twelve right angle turns between the distribution point and the units. Conventional fiber would lose the signal after one or two such bends, making it useless in this role. [4] As is the case for individual homes, the fiber can be converted to copper for the last section of delivery, but the longer runs demand much higher performance, larger cable. Finding room to run these cables in an existing structure may not be possible.

ClearCurve

ClearCurve fibers are constructed in a fashion similar to existing cables, starting with a traditional glass fiber in the center. ClearCurve then adds a third layer to the sandwich, a plastic sheath that is infused with microscopic reflectors. Light that passes through the conventional interface has a second chance to be reflected back into the center of the fiber. In the corners of tight bends, the reflectors serve to increase the amount of signal retained within the cable, allowing ClearCurve to be hundreds of times more flexible than conventional cables. [5] [6] A thin environmental sheath is added on the outside.

Unlike conventional fibers, ClearCurve does not have to be held straight, and therefore eliminates the armour. Lacking armour, there is no lower limit to the size of a ClearCurve cable, which can be as small as a single fiber, although normally they contain two fibres, one upstream and one down. Two-fiber ClearCurve cables are smaller than the wire on a typical computer mouse, yet the high-performance single-mode versions carry 25 Gbit/s over long lengths. [7]

In a video demonstration, Corning showed a ClearCurve drop cable being wrapped dozens of times around a small metal rod, and suffering almost no signal loss and providing a perfect video feed. A conventional cable wrapped around the same rod completely lost the signal after only two turns.

FTTH uses

ClearCurve is the end result of a Corning research project looking for products better tailored to the fiber to the home market. [6] Running since 1988 at their Sullivan Park research center in New York, Corning announced ClearCurve at a press event on 19 September 2007 and showed it publicly at the FTTH Conference later that month. [8]

Using ClearCurve, a FTTH installation can use existing armoured cabling to deliver the signal to a utility room, then connect individual ClearCurve cables to the fibers in the bundle for distribution within the building. This sort of installation dramatically simplifies the overall complexity of FTTH wiring in multi-unit dwellings, eliminating both the large coax cabling and the need to convert formats from light to electrical. Users were quickly forthcoming; announced in September, only a month later an official press release announced that Connexion Technologies would be using ClearCurve on 30 November 2007. [9] Since then many additional partners have been announced.

Computer bus uses

The single-mode fibers used in conversional telecommunications applications have high performance, but require expensive light sources and highly accurate mechanical positioning in order to gather light from them. In comparison, multi-mode have wider cores that are easier to connect to and can be effectively driven by lower-cost devices like solid-state IR lasers or vertical-cavity surface-emitting lasers (VCSELs). [10]

Multi-mode fiber found some uses in high-performance computing applications, notably the Fibre Channel system for high speed disks and some parallel computing interconnection systems. However, the relatively inflexible cables made them less useful in general roles, where braided copper wiring remains widespread. Fiber has found one consumer use, the TOSLINK cable used in digital audio applications. This role uses lower quality multi-mode plastic fibre with limited bandwidth, about 125 Mbit/s, driven by red LEDs. However, advances in computers have demanded ever increasing bandwidth, and modern computer bus systems are quickly reaching their limits. There was some discussion of moving to optical fiber for the USB3 standard, but the decision was made to move ahead with copper. [11]

Corning announced a multi-mode version of ClearCurve cabling on 13 January 2009. [12] It has greater bandwidth than any common copper wiring, and is at least as flexible as copper wiring able to carry the same amount of data. Although it was mentioned only in passing, Intel's new Light Peak interconnection system uses ClearCurve cabling as its basis. [13] Light Peak uses a two-fiber cable running at 10 Gbit/s in both directions. Unlike most optical connection systems, Light Peak is being designed to allow daisy-chaining and supply power through a set of coaxial copper wires.

Related Research Articles

<span class="mw-page-title-main">Single-mode optical fiber</span> Optical fiber designed to carry only a single mode of light, the transverse mode

In fiber-optic communication, a single-mode optical fiber (SMF), also known as fundamental- or mono-mode, is an optical fiber designed to carry only a single mode of light - the transverse mode. Modes are the possible solutions of the Helmholtz equation for waves, which is obtained by combining Maxwell's equations and the boundary conditions. These modes define the way the wave travels through space, i.e. how the wave is distributed in space. Waves can have the same mode but have different frequencies. This is the case in single-mode fibers, where we can have waves with different frequencies, but of the same mode, which means that they are distributed in space in the same way, and that gives us a single ray of light. Although the ray travels parallel to the length of the fiber, it is often called transverse mode since its electromagnetic oscillations occur perpendicular (transverse) to the length of the fiber. The 2009 Nobel Prize in Physics was awarded to Charles K. Kao for his theoretical work on the single-mode optical fiber. The standards G.652 and G.657 define the most widely used forms of single-mode optical fiber.

<span class="mw-page-title-main">Transmission medium</span> Conduit for signal propagation

A transmission medium is a system or substance that can mediate the propagation of signals for the purposes of telecommunication. Signals are typically imposed on a wave of some kind suitable for the chosen medium. For example, data can modulate sound, and a transmission medium for sounds may be air, but solids and liquids may also act as the transmission medium. Vacuum or air constitutes a good transmission medium for electromagnetic waves such as light and radio waves. While material substance is not required for electromagnetic waves to propagate, such waves are usually affected by the transmission media they pass through, for instance, by absorption or reflection or refraction at the interfaces between media. Technical devices can therefore be employed to transmit or guide waves. Thus, an optical fiber or a copper cable is used as transmission media.

<span class="mw-page-title-main">Electrical cable</span> Assembly of one or more wires running side by side or bundled

An electrical cable is an assembly of one or more wires running side by side or bundled, which is used to carry electric current.

<span class="mw-page-title-main">Gigabit Ethernet</span> Standard for Ethernet networking at a data rate of 1 gigabit per second

In computer networking, Gigabit Ethernet is the term applied to transmitting Ethernet frames at a rate of a gigabit per second. The most popular variant, 1000BASE-T, is defined by the IEEE 802.3ab standard. It came into use in 1999, and has replaced Fast Ethernet in wired local networks due to its considerable speed improvement over Fast Ethernet, as well as its use of cables and equipment that are widely available, economical, and similar to previous standards. The first standard for faster 10 Gigabit Ethernet was approved in 2002.

<span class="mw-page-title-main">Optical fiber connector</span>

An optical fiber connector joins optical fibers, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so light can pass. Better connectors lose very little light due to reflection or misalignment of the fibers. In all, about 100 different types of fiber optic connectors have been introduced to the market.

<span class="mw-page-title-main">Multi-mode optical fiber</span> Type of optical fiber mostly used for communication over short distances

Multi-mode optical fiber is a type of optical fiber mostly used for communication over short distances, such as within a building or on a campus. Multi-mode links can be used for data rates up to 100 Gbit/s. Multi-mode fiber has a fairly large core diameter that enables multiple light modes to be propagated and limits the maximum length of a transmission link because of modal dispersion. The standard G.651.1 defines the most widely used forms of multi-mode optical fiber.

<span class="mw-page-title-main">Optical fiber</span> Light-conducting fiber

An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths than electrical cables. Fibers are used instead of metal wires because signals travel along them with less loss; in addition, fibers are immune to electromagnetic interference, a problem from which metal wires suffer. Fibers are also used for illumination and imaging, and are often wrapped in bundles so they may be used to carry light into, or images out of confined spaces, as in the case of a fiberscope. Specially designed fibers are also used for a variety of other applications, some of them being fiber optic sensors and fiber lasers.

Fiber to the <i>x</i> Broadband network architecture term

Fiber to the x or fiber in the loop is a generic term for any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications. As fiber optic cables are able to carry much more data than copper cables, especially over long distances, copper telephone networks built in the 20th century are being replaced by fiber.

Optical networking is a means of communication that uses signals encoded in light to transmit information in various types of telecommunications networks. These include limited range local-area networks (LAN) or wide-area networks (WAN), which cross metropolitan and regional areas as well as long-distance national, international and transoceanic networks. It is a form of optical communication that relies on optical amplifiers, lasers or LEDs and wave division multiplexing (WDM) to transmit large quantities of data, generally across fiber-optic cables. Because it is capable of achieving extremely high bandwidth, it is an enabling technology for the Internet and telecommunication networks that transmit the vast majority of all human and machine-to-machine information.

Ethernet in the first mile (EFM) refers to using one of the Ethernet family of computer network technologies between a telecommunications company and a customer's premises. From the customer's point of view, it is their first mile, although from the access network's point of view it is known as the last mile.

<span class="mw-page-title-main">Light tube</span> Architectural element

Light tubes are structures that transmit or distribute natural or artificial light for the purpose of illumination and are examples of optical waveguides.

<span class="mw-page-title-main">Fiber-optic communication</span> Method of transmitting information

Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of infrared light through an optical fiber. The light is a form of carrier wave that is modulated to carry information. Fiber is preferred over electrical cabling when high bandwidth, long distance, or immunity to electromagnetic interference is required. This type of communication can transmit voice, video, and telemetry through local area networks or across long distances.

<span class="mw-page-title-main">Fiber-optic cable</span> Cable assembly containing one or more optical fibers that are used to carry light

A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable but containing one or more optical fibers that are used to carry light. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable is used. Different types of cable are used for optical communication in different applications, for example long-distance telecommunication or providing a high-speed data connection between different parts of a building.

Networking cables are networking hardware used to connect one network device to other network devices or to connect two or more computers to share devices such as printers or scanners. Different types of network cables, such as coaxial cable, optical fiber cable, and twisted pair cables, are used depending on the network's topology, protocol, and size. The devices can be separated by a few meters or nearly unlimited distances.

<span class="mw-page-title-main">10 Gigabit Ethernet</span> Standards for Ethernet at ten times the speed of Gigabit Ethernet

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Cladding in optical fibers is one or more layers of materials of lower refractive index in intimate contact with a core material of higher refractive index. The cladding causes light to be confined to the core of the fiber by total internal reflection at the boundary between the core and cladding. Light propagation within the cladding is typically suppressed for most fibers. However, some fibers can support cladding modes in which light propagates through the cladding as well as the core. Depending upon the quantity of modes that are supported, they are referred to as multi-mode fibers and single-mode fibers. Improving transmission through fibers by applying a cladding was discovered in 1953 by Dutch scientist Bram van Heel.

A fiber-optic patch cord is a fiber-optic cable capped at either end with connectors that allow it to be rapidly and conveniently connected to CATV, an optical switch or other telecommunication equipment. Its thick layer of protection is used to connect the optical transmitter, receiver, and the terminal box. This is known as "interconnect-style cabling".

Subisu Cablenet Ltd. is a Nepalese Internet Service Provider company located in Kathmandu, Nepal, and was established in 2001. Subisu employs over 1500 full-time employees, of which around 900 are technical, and around 700 are non-technical. As of 2023, the company has over 235,000 customers. It has coverage at all 77 districts of Nepal. Subisu primarily provides cable & fiber internet and Digital TV services through a hybrid fiber-coaxial (HFCC) network. Internet and 280+ TV channels that it offers provides a strong spine to Nepal's educational, entertainment, professional and other sectors. It is the first and the only cable internet service provider in Nepal.

References

  1. ↑ Craig Freudenrich, "How Fiber Optics Work", How Stuff Works
  2. ↑ ""The Basics of Fiber Optical Cable"". Archived from the original on 2018-10-23. Retrieved 2009-10-11.
  3. ↑ "Definition of Terms", FTTH Council, 9 January 2009
  4. ↑ "The ultimately flexible fiber" Archived 2010-01-05 at the Wayback Machine , Corning, 2009
  5. ↑ "Bend the rules", Corning, 2009
  6. 1 2 Stephanie Mehta, "Bend It Like Corning" Archived 2011-06-12 at the Wayback Machine , Fortune, 6 August 2007.
  7. ↑ "Nearly unlimited bandwidth for broadband" Archived 2010-01-06 at the Wayback Machine , Corning, 2009
  8. ↑ "Corning to Introduce ClearCurve Product Suite at FTTH Conference" Archived 2011-06-12 at the Wayback Machine , Corning press release, 19 September 2007
  9. ↑ "Corning Cable Systems Announces First Sale of ClearCurve Product Solution", Business Wire, 30 November 2007
  10. ↑ "Mode Theory" Archived 2009-12-15 at the Wayback Machine , Navy Electricity and Electronics Training Series
  11. ↑ Stephen Shankland, "USB 3.0 brings optical connection in 2008", cnet, 18 September 2007
  12. ↑ "Corning Announces Multimode Version of ClearCurve Optical Fiber" Archived 2009-04-11 at the Wayback Machine , Corning press release, 13 January 2009
  13. ↑ Brooke Crothers, "Sources: 'Light Peak' technology not Apple idea" Archived 2010-06-23 at the Wayback Machine , cnet news, 29 September 2009
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