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Single Fiber Optic Cable Sets New World Record

The National Institute of Information and Communications in Tokyo has achieved a world speed record of sending 109 terabits per second over a single fiber optic cable. The optical fiber cable the team used contained a single fiber with seven “light-guiding cores,” whereas a regular fiber optic cable contains a single core. Each core managed to carry 15.6 terabits per second.

Tim Strong of TeleGeography Research says that the new record speed is far beyond the world’s current capacity, as the total capacity of one of the world’s busiest routes, between New York and Washington D.C., is only a few terabits per second, a speed dwarfed by the 109 terabits per second record. Strong does point out, however, that traffic has been growing 50 percent each year for the past few years.

The runner-up record-setter, Dayou Qian, achieved a speed of 101.7 terabits per second using a method that employed 370 separate lasers, each one carrying a small amount of information, but combining to form a large, single data transfer sent down 165 kilometers of fiber optics.

Though these speeds aren’t practically applied anywhere as of yet, it’s not a stretch to think huge data centers may be using these methods of data transfer soon, as we live in a world dominated by the Internet, and companies like Google and Amazon are gigantic and show no signs of slowing down anytime soon. 7DNG2S92MQHH

Source: fiber optic cable supplier

What are Fiber Optic Attenuators

Fiber optic attenuators are used in applications where the optical signal is too strong and needs to be reduced. For example, in a multi-wavelength fiber optic system, you need to equalize the optical channel strength so that all the channels have similar power levels. This means to reduce stronger channels’ powers to match lower power channels.

The attenuation level is fixed at 5 dB, which means it reduces the optical power by 5dB. This attenuator has a short piece of fiber with metal ion doping that provides the specified attenuation.

There are many different mechanisms to reduce the optical power, this picture shows another mechanism used in one type of variable attenuator. Here variable means the attenuation level can be adjusted, for example, it could be from 1 dB up to 20dB.

Fiber optic attenuators are usually used in two scenarios.

The first case is in fiber optic power level testing. Attenuators are used to temporarily add a calibrated amount of signal loss in order to test the power level margins in a fiber optic communication system.

In the second case, attenuators are permanently installed in a fiber optic communication link to properly match transmitter and receiver optical signal levels.

Optical attenuators are typically classified as fixed or variable attenuators.

Fixed attenuators have a fixed optical power reduction number, such as 1dB, 5dB, 10dB, etc.

Variable attenuators’ attenuation level can be adjusted, such as from 0.5 dB to 20dB, or even 50dB. Some variable attenuators have very fine resolution, such as 0.1dB, or even 0.01dB.

This slide shows many different optical attenuator designs.

The female to female fixed attenuators work like a regular adapter. But instead of minimizing insertion loss, it purposely adds some attenuation.

The female to female variable attenuators are adjustable by turning a nut in the middle. The nut adjusts the air gap in the middle to achieve different attenuation levels.

The male to female fixed attenuators work as fiber connectors, you can just plug in your existing fiber connector to its female side.

The in-line patch cable type variable attenuators work as regular patch cables, but your can adjust its attenuation level by turning the screw.

For precise testing purposes, engineers have also designed instrument type variable attenuators. These instrument type attenuators have high attenuation ranges, such as from 0.5 dB to 70dB. They also have very fine resolution, such as 0.01dB. This is critical for accurate testing.

Source: fiber optic cable manufacturer

Fiber Optic Cable Plant Link Loss Budget Analysis

Loss budget analysis is the calculation and verification of a fiber optic system’s operating characteristics. This encompasses items such as routing, electronics, wavelengths, fiber type, and circuit length. Attenuation and bandwidth are the key parameters for budget loss analysis.

Analyze Fiber Optic Link Loss In The Design Stage
Prior to designing or installing a fiber optic system, a loss budget analysis is reccommended to make certain the system will work over the proposed link. Both the passive and active components of the circuit have to be included in the budget loss calculation. Passive loss is made up of fiber loss, connector loss, and splice loss. Don’t forget any couplers or splitters in the link. Active components are system gain, wavelength, transmitter power, receiver sensitivity, and dynamic range. Prior to system turn up, test the circuit with a source and FO power meter to ensure that it is within the loss budget.

The idea of a loss budget is to insure the network equipment will work over the installed fiber optic link. It is normal to be conservative over the specifications! Don’t use the best possible specs for fiber attenuation or connector loss – give yourself some margin!

The best way to illustrate calculating a loss budget is to show how it’s done for a 2 km multimode link with 5 connections (2 connectors at each end and 3 connections at fiber optic patch panels in the link) and one splice in the middle. See the drawings below of the link layout and the instantaneous power in the link at any point along it’s length, scaled exactly to the link drawing above it.

Fiber Optic Cable Plant Passive Component Loss

Step 1. Fiber loss at the operating wavelength

Cable Length 2.0 2.0
Fiber Type Multimode Singlemode
Wavelength (nm) 850 1300 1300 1550
Fiber Atten. dB/km 3 [3.5] 1 [1.5] 0.4 [1/0.5] 0.3 [1/0.5]
Total Fiber Loss 6.0 [7.0] 2.0 [3.0]

Step 2. Connector Loss
Multimode connectors will have losses of 0.2-0.5 dB typically. Singlemode connectors, which are factory made and fusion spliced on will have losses of 0.1-0.2 dB. Field terminated singlemode connectors may have losses as high as 0.5-1.0 dB. Let’s calculate it at both typical and worst case values.

Connector Loss 0.3 dB (typical adhesive/polish conn) 0.75 dB (TIA-568 max acceptable)
Total # of Connectors 5 5
Total Connector Loss 1.5 dB 3.75 dB

(All connectors are allowed 0.75 max per EIA/TIA 568 standard)

Step 3. Splice Loss
Multimode splices are usually made with mechanical splices, although some fusion splicing is used. The larger core and multiple layers make fusion splicing abut the same loss as mechanical splicing, but fusion is more reliable in adverse environments. Figure 0.1-0.5 dB for multimode splices, 0.3 being a good average for an experienced installer. Fusion splicing of singlemode fiber will typically have less than 0.05 dB (that’s right, less than a tenth of a dB!)

Typical Splice Loss 0.3 dB
Total # splices 1
Total Splice Loss 0.3 dB

(All splices are allowed 0.3 max per EIA/TIA 568 standard)

Step 4. Total Passive System Attenuation
Add the fiber loss, connector and splice losses to get the link loss.

Best Case TIA 568 Max
850 nm 1300 nm 850 nm 1300 nm
Total Fiber Loss (dB) 6.0 2.0 7.0 3.0
Total Connector Loss (dB) 1.5 1.5 3.75 3.75
Total Splice Loss (dB) 0.3 0.3 0.3 0.3
Other (dB) 0 0 0 0
Total Link Loss (dB) 7.8 3.8 11.05 7.05

Remember these should be the criteria for testing. Allow +/- 0.2 -0.5 dB for measurement uncertainty and that becomes your pass/fail criterion.

Equipment Link Loss Budget Calculation: Link loss budget for network hardware depends on the dynamic range, the difference between the sensitivity of the receiver and the output of the source into the fiber. You need some margin for system degradation over time or environment, so subtract that margin (as much as 3dB) to get the loss budget for the link.

Step 5. Data From Manufacturer’s Specification for Active Components (Typical 100 Mb/s link)

Operating Wavelength (nm) 1300
Fiber Type MM
Receiver Sens. (dBm@ required BER) -31
Average Transmitter Output (dBm) -16
Dynamic Range (dB) 15
Recommended Excess Margin (dB) 3

Step 6. Loss Margin Calculation

Dynamic Range (dB) (above) 15 15
Cable Plant Link Loss (dB) 3.8 (Typ) 7.05 (TIA)
Link Loss Margin (dB) 11.2 7.95

As a general rule, the Link Loss Margin should be greater than approximately 3 dB to allow for link degradation over time. LEDs in the transmitter may age and lose power, connectors or splices may degrade or connectors may get dirty if opened for rerouting or testing. If cables are accidentally cut, excess margin will be needed to accommodate splices for restoration.

Source: http://www.jfiberoptic.com, fiber optic cables

City of Mayville to get fiber optic lines after all

In early May, finance chair Kathy Sertich said it was bad timing to pay for the installation of fiber optic from the school district. Now, it seems there is no time like the present.

The Mayville Common Council approved Monday evening an agreement with the Mayville School District to run fiber optic cable to City Hall to allow the police department to have high-speed access to security cameras at the schools with no cost to the city.

“The school district of Mayville proposes to install six strands of fiber to the city of Mayville as part of the district’s infrastructure upgrade at the school district’s cost,” said Sue Wery, technology director for the district.

Only two of those strands will be used at this time to allow police to connect to the cameras. The other four will be built in for future expansion at City Hall. The city will also not have to pay for any equipment needed for monitoring. The installation is slated for July/August.

“I think this is a great thing and I am glad,” Sertich said. “Thank you, because at this point we could not do it with the deficit that we’re still covering.”

On May 8, the city held a meeting in which it was determined that a fiber optic tie-in was not financially feasible due to a strict nine-year plan to pull the city out of debt. It was estimated to cost $5,800.

On May 22, the district was put on lockdown during a weapons scare which highlighted some shortcomings in the security plan. On June 11, the Wisconsin Board of Commissioners of Public Lands approved a $225,000 loan to the district for the project.

Wery said that hopefully next year they can apply for another grant that would reimburse them for the cost of the tie in as well as getting more cameras in the future.

“We didn’t want to incur any additional charges for you to have to come back next year and do it,” said John Westphal, school board president.

Source: fiber optic connectors

The Different Types of Fiber Optic Attenuators

LC/PC Fixed Fiber optic attenuator

LC/PC Fixed Fiber optic attenuator

Fiber optic attenuator is used in the fiber optic communications to reduce the optical fiber power at a certain level, the most commonly used type is female to male plug type fiber optic attenuator, it has the optical fiber connector at one side and the other side is a female type fiber optic adapter, fiber optic attenuator name is based on the connector type and the attenuation level.

There are two functional types of fiber attenuators: plug style (including bulkhead) and in-line.

A plug style attenuator is employed as a male-female connector where attenuation occurs inside the device, that is, on the light path from one ferrule to another. These include FC fiber optic attenuator, LC attenuator, SC attenuator, ST attenuator and more.

An in-line attenuator is connected to a transmission fiber by splicing its two pigtails.

The principle of operation of attenuators are markedly different because they use various phenomena to decrease the power of the propagating light. The simplest means is to bend a fiber. Coil a patch cable several times around a pencil while measuring the attenuation with a power meter, then tape this coil. Then you got a primitive but working attenuator.

Most attenuators have fixed values that are specified in decibels (dB). They are called fiber optic fixed attenuator. For example, a -3dB attenuator should reduce intensity of the output by 3dB.

Manufacturers use various types of light-absorbing material to achieve well-controlled and stable attenuation. For example, a fiber doped with a transition metal that absorbs light in a predictable way and disperses absorbed energy as a heat.

Variable fiber optic attenuators also are available, but they usually are precision instruments used in making measurements.

Jfiberoptic offers many high quality Fiber Optic Attenuators, including FC,LC,ST Fiber Attenuators, both single mode and multimode.

Source: Jfiberoptic.com

What is Multi-mode fiber?

Fiber with large core diameter (greater than 10 micrometers) may be analyzed by geometrical optics. Such fiber is called multi-mode fiber, from the electromagnetic analysis (see below). In a step-index multi-mode fiber, rays of light are guided along the fiber core by total internal reflection. Rays that meet the core-cladding boundary at a high angle (measured relative to a line normal to the boundary), greater than the critical angle for this boundary, are completely reflected. The critical angle (minimum angle for total internal reflection) is determined by the difference in index of refraction between the core and cladding materials. Rays that meet the boundary at a low angle are refracted from the core into the cladding, and do not convey light and hence information along the fiber. The critical angle determines the acceptance angle of the fiber, often reported as a numerical aperture. A high numerical aperture allows light to propagate down the fiber in rays both close to the axis and at various angles, allowing efficient coupling of light into the fiber. However, this high numerical aperture increases the amount of dispersion as rays at different angles have different path lengths and therefore take different times to traverse the fiber.

Optical fiber types.

 

A laser bouncing down an acrylic rod, illustrating the total internal reflection of light in a multi-mode optical fiber.

The propagation of light through a multi-mode optical fiber.

In graded-index fiber, the index of refraction in the core decreases continuously between the axis and the cladding. This causes light rays to bend smoothly as they approach the cladding, rather than reflecting abruptly from the core-cladding boundary. The resulting curved paths reduce multi-path dispersion because high angle rays pass more through the lower-index periphery of the core, rather than the high-index center. The index profile is chosen to minimize the difference in axial propagation speeds of the various rays in the fiber. This ideal index profile is very close to a parabolic relationship between the index and the distance from the axis.

Related fiber optical products:

Optical fiber communication

Optical fiber can be used as a medium for telecommunication and computer networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. This allows long distances to be spanned with few repeaters. Additionally, the per-channel light signals propagating in the fiber have been modulated at rates as high as 111 gigabits per second by NTT, although 10 or 40 Gbit/s is typical in deployed systems. Each fiber can carry many independent channels, each using a different wavelength of light (wavelength-division multiplexing (WDM)). The net data rate (data rate without overhead bytes) per fiber is the per-channel data rate reduced by the FEC overhead, multiplied by the number of channels (usually up to eighty in commercial dense WDM systems as of 2008). As of 2011 the record for bandwidth on a single core was 101 Tbit/sec (370 channels at 273 Gbit/sec each). The record for a multi-core fibre as of January 2013 was 1.05 petabits per second. In 2009, Bell Labs broke the 100 (Petabit per second)×kilometre barrier (15.5 Tbit/s over a single 7000 km fiber).

For short distance application, such as a network in an office building, fiber-optic cabling can save space in cable ducts. This is because a single fiber can carry much more data than electrical cables such as standard category 5 Ethernet cabling, which typically runs at 100 Mbit/s or 1 Gbit/s speeds. Fiber is also immune to electrical interference; there is no cross-talk between signals in different cables, and no pickup of environmental noise. Non-armored fiber cables do not conduct electricity, which makes fiber a good solution for protecting communications equipment in high voltage environments, such as power generation facilities, or metal communication structures prone to lightning strikes. They can also be used in environments where explosive fumes are present, without danger of ignition. Wiretapping (in this case, fiber tapping) is more difficult compared to electrical connections, and there are concentric dual core fibers that are said to be tap-proof.

Related fiber optic products: fiber optic patch cable, fiber optic jumper, fiber optic pigtail

The History about fiber optics

Fiber optics, though used extensively in the modern world, is a fairly simple, and relatively old, technology. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London, 12 years later. Tyndall also wrote about the property of total internal reflection in an introductory book about the nature of light in 1870: “When the light passes from air into water, the refracted ray is bent towards the perpendicular… When the ray passes from water to air it is bent from the perpendicular… If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the ray will not quit the water at all: it will be totally reflected at the surface…. The angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27′, for flint glass it is 38°41′, while for diamond it is 23°42′.” Unpigmented human hairs have also been shown to act as an optical fiber.

Practical applications, such as close internal illumination during dentistry, appeared early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. The principle was first used for internal medical examinations by Heinrich Lamm in the following decade. Modern optical fibers, where the glass fiber is coated with a transparent cladding to offer a more suitable refractive index, appeared later in the decade. Development then focused on fiber bundles for image transmission. Harold Hopkins and Narinder Singh Kapany at Imperial College in London achieved low-loss light transmission through a 75 cm long bundle which combined several thousand fibers. Their article titled “A flexible fibrescope, using static scanning” was published in the journal Nature in 1954. The first fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, and Lawrence E. Curtiss, researchers at the University of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers; previous optical fibers had relied on air or impractical oils and waxes as the low-index cladding material.

A variety of other image transmission applications soon followed.

In 1880 Alexander Graham Bell and Sumner Tainter invented the ‘Photophone’ at the Volta Laboratory in Washington, D.C., to transmit voice signals over an optical beam. It was an advanced form of telecommunications, but subject to atmospheric interferences and impractical until the secure transport of light that would be offered by fiber-optical systems. In the late 19th and early 20th centuries, light was guided through bent glass rods to illuminate body cavities.Jun-ichi Nishizawa, a Japanese scientist at Tohoku University, also proposed the use of optical fibers for communications in 1963, as stated in his book published in 2004 in India. Nishizawa invented other technologies that contributed to the development of optical fiber communications, such as the graded-index optical fiber as a channel for transmitting light from semiconductor lasers. The first working fiber-optical data transmission system was demonstrated by German physicist Manfred Börner at Telefunken Research Labs in Ulm in 1965, which was followed by the first patent application for this technology in 1966.Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables (STC) were the first to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer (dB/km), making fibers a practical communication medium. They proposed that the attenuation in fibers available at the time was caused by impurities that could be removed, rather than by fundamental physical effects such as scattering. They correctly and systematically theorized the light-loss properties for optical fiber, and pointed out the right material to use for such fibers — silica glass with high purity. This discovery earned Kao the Nobel Prize in Physics in 2009.

NASA used fiber optics in the television cameras that were sent to the moon. At the time, the use in the cameras was classified confidential, and only those with the right security clearance or those accompanied by someone with the right security clearance were permitted to handle the cameras.

The crucial attenuation limit of 20 dB/km was first achieved in 1970, by researchers Robert D. Maurer, Donald Keck, Peter C. Schultz, and Frank Zimar working for American glass maker Corning Glass Works, now Corning Incorporated. They demonstrated a fiber with 17 dB/km attenuation by doping silica glass with titanium. A few years later they produced a fiber with only 4 dB/km attenuation using germanium dioxide as the core dopant. Such low attenuation ushered in optical fiber telecommunication. In 1981, General Electric produced fused quartz ingots that could be drawn into fiber optic strands 25 miles (40 km) long.

Attenuation in modern optical cables is far less than in electrical copper cables, leading to long-haul fiber connections with repeater distances of 70–150 kilometers (43–93 mi). The erbium-doped fiber amplifier, which reduced the cost of long-distance fiber systems by reducing or eliminating optical-electrical-optical repeaters, was co-developed by teams led by David N. Payne of the University of Southampton and Emmanuel Desurvire at Bell Labs in 1986. Robust modern optical fiber uses glass for both core and sheath, and is therefore less prone to aging. It was invented by Gerhard Bernsee of Schott Glass in Germany in 1973.

The emerging field of photonic crystals led to the development in 1991 of photonic-crystal fiber, which guides light by diffraction from a periodic structure, rather than by total internal reflection. The first photonic crystal fibers became commercially available in 2000. Photonic crystal fibers can carry higher power than conventional fibers and their wavelength-dependent properties can be manipulated to improve performance.

Related fiber optic products: fiber optic patch cord, fiber optic patch panel, fiber optic connector

Prysmian opens new fiber-optic cable plant in Romania

Cable maker Prysmian Group says it has a new fiber-optic cable production facility at its campus in Slatina, Romania. The new production capability will triple the factory’s fiber-optic cable capacity to 1.5 million km, with the potential to reach 3 million km.

Prysmian manufactures energy cable and copper cable as well as fiber cable at the 40-year-old Slatina factory, one of 24 production facilities the company operates worldwide. The site began producing fiber-optic cable in 2009. The plant comprises almost 100,000 m2 of space, 42,000 m2 of it covered, and employs more than 400 people.

“The investment in the new facility in Slatina is part of a major plan to further reinforce the Group’s competitiveness in this fast-changing market,” said Valerio Battista, CEO of the Prysmian Group. “Many developments are taking place in the current telecoms market. New players and services are appearing and evolution in broadband, double-play and triple-play services is dynamic. For this reason, as one of the major players in the telecom cable industry, Prysmian Group is continuously investing in this strategic sector in order to offer innovative technological solutions for the development of telecoms networks.”