Learn about EDFA equipment in few minutes

by www.fiber-mart.com

WDM EDFA used to combine CATV signal from optical transmitter with internet signal from OLT and output to single fiber.

 

EDFA product overview

 

An Erbium-Doped Fiber Amplifier (EDFA) is a device that amplifies an optical fiber signal (from CATV). An WDM EDFA is used to integrated 1550nm CATV (optical signal) and 1490nm /1310nm data stream from the PON into single fiber transmission.

 

FOT EDFA series of products adopt 980nm or 1480nm high linearity, optical isolation, the DFB, thermoelectric cooling DFB laser produced by JDS, Fujitsu, Nortel, Lucent, Fitel and other world-renowned semiconductor companies as the pumping source.

 

In the interior of the machine is equipped with the light power export stable circuit and laser Thermoelectric cooling device Temperature stability control circuit to ensure optimal machine performance and long-life laser stability. The microprocessor software monitor the lasers’ working state, the Digital Panel (VFD) displays the operating parameters. Once the laser operating parameters deviate from the permissible range set by the software, micro-processing will automatically turn off laser power, red light goes on to warn, digital panel prompts cause of troubles., a detailed report of the device parameters please read FOT EDFA user manual.

 

EDFA and optical communications

EDFA (Erbium Doped Fiber Amplifier) is a representative one in the optical amplifier. As the EDFA’s wavelength is 1550nm, it is in line with the low-loss band of fiber and its technology has been relatively mature, so widely used.

 

Erbium-doped fiber is the core components of the EDFA, it makes quartz optical fiber as matrix material, and incorporate a certain proportion of rare earth element erbium ions (Er3 +) in the core of a fiber. When certain amount of pump light is injected into the erbium-doped fiber, Er3 + have been excited from the low-energy level to the high energy level, due to Er3 + has a very short lifespan on the high energy level, and soon transit to a higher level by the form of a non-radiative, and form the population inversion distribution between this energy level and low-energy-level. Because the energy between these two energy levels is exactly equal to the photon energy of 1550nm, stimulated emission of 1550nm light can only occur, we can only enlarge 1550nm optical signal.

 

EDFA has revolutionized optical communications

All optical and fiber compatible

Wide bandwidth, 20~70 nm

High gain, 20~40 dB

High output power, >200mW

Bit rate, modulation fromat, power and wavelength insensitive

Low distortion and low noise (NF<5dB)

 

Basic principle of EDFA

A relatively high-powered beam of light is mixed with the input signal using a wavelength selective coupler. The input signal and the excitation light must be at significantly different wavelengths. The mixed light is guided into a section of fibre with erbium ions included in the core. This high-powered light beam excites the erbium ions to their higher-energy state. When the photons belonging to the signal at a different wavelength from the pump light meet the excited erbium atoms, the erbium atoms give up some of their energy to the signal and return to their lower-energy state.

 

A significant point is that the erbium gives up its energy in the form of additional photons which are exactly in the same phase and direction as the signal being amplified. So the signal is amplified along its direction of travel only. This is not unusual – when an atom “lases” it always gives up its energy in the same direction and phase as the incoming light. Thus all of the additional signal power is guided in the same fibre mode as the incoming signal. There is usually an isolator placed at the output to prevent reflections returning from the attached fibre. Such reflections disrupt amplifier operation and in the extreme case can cause the amplifier to become a laser. The erbium doped amplifier is a high gain amplifier.

Technology Of Fiber Optic Amplifiers

by www.fiber-mart.com

In fiber optic communication, the visible-light or infrared (IR) beams carried by a fiber are attenuated as they travel through the material. Then there comes to the fiber optic amplifier which is used to compensate for the wakening of information during the transmission.

 

Amplifiers are inserted at specific places to boost optical signals in a system where the signals are weak. This boost allows the signals to be successfully transmitted through the remaining cable length. In large networks, a long series of optical fiber amplifiers are placed in a sequence along the entire network link.

 

Common fiber optical amplifiers include Erbium-Doped Fiber Amplifier (or EDFA Optical Amplifier), Raman fiber amplifier, and silicon optical amplifier (SOA). Erbium doped fiber amplifier is the major type of the fiber amplifier used to boost the signal in the WDM fiber optic system, as we know it is WDM that increase the capacity of the fiber communications system and it is the erbium-doped fiber amplifier that makes WDM transmission possible. Fiber amplifiers are developed to support Dense Wavelength Division Multiplexing (DWDM) which is called DWDM EDFA amplifier and to expand to the other wavelength bands supported by fiber optics.

 

There are several different physical mechanisms that can be used to amplify a light signal, which correspond to the major types of optical amplifiers. In doped fibre amplifiers and bulk lasers, stimulated emission in the amplifier’s gain medium causes amplification of incoming light. In semiconductor optical amplifiers (SOAs), electron-hole recombination occurs. In Raman amplifiers, Raman scattering of incoming light with phonons in the lattice of the gain medium produces photons coherent with the incoming photons. Parametric amplifiers use parametric amplification.

 

When light is transmitted through matter, part of the light is scattered in random directions. A small part of the scattered light has frequencies removed from the frequency of the incident beam by quantities equal to the vibration frequencies of the material scattering system. Raman fiber optic amplifiers function within this small scattering range. If the initial beam is sufficiently intense and monochromatic, a threshold can be reached beyond which light at the Raman frequencies is amplified, builds up strongly, and generally exhibits the characteristics of stimulated emission. This is called the stimulated or coherent Raman effect.

 

EFDA fiber optic amplifier functions by adding erbium, rare earth ions, to the fiber core material as a dopant; typically in levels of a few hundred parts per million. The fiber is highly transparent at the erbium lasing wavelength of two to nine microns. When pumped by a laser diode, optical gain is created, and amplification occurs.

 

Silicon or semiconductor optical amplifier functions in a similar way to a basic laser. The structure is much the same, with two specially designed slabs of semiconductor material on top of each other, with another material in between them forming the “active layer”. An electrical current is set running through the device in order to excite electrons which can then fall back to the non-excited ground state and give out photons. Incoming optical signal stimulates emission of light at its own wavelength.

 

Fiber optic repeater also can re-amplify an attenuated signal but it can only function on a specific wavelength and is not suitable for WDM systems. That is the reason why fiber optic amplifier plays a much more important role in communication systems.

10GBASE-T – Will It be the Best Media Options for 10G Data Center?

by Fiber-MART.COM

Ratified in 2006, 10GBASE-T is the standard to provide 10Gbqs connections over balanced twisted-pair copper, including Category 6A unshielded and shielded cabling. It provides great flexibility in network design due to its 100-meter reach capability. An immediate use for 10GBASE-T is to build the data center access-layer network that connects servers to access switches. But is it the best options for 10G data center? Understanding this requires an examination of the pros and cons of current 10GbE media options.

 

10GBASE-CX4

10GBASE-CX4 was the first favorite for 10GbE deployments, however its adoption was limited by the bulky and expensive cables, and its reach is limited to 15 meters. The large size of the CX4 connector prohibited higher switch densities required for large scale deployment. Larger diameter cables like 10GBASE-CX4 are purchased in fixed lengths resulting in challenges to manage cable slack. As a result, pathways and spaces may not be sufficient to handle this larger cable.

 

SFP+

SFP+’s support for both fiber optic cables and DAC which makes it a better solution than CX4. SFP+ is commonly used for 10G today, but it has limitations that will prevent itself from moving to every server. The following image shows a SFP+ nodule, SFP+ DAC cable and a 10GBASE-T SFP+ port media converter.

 

10GBASE-SR—10GBASE-SR (SFP+ fiber) fiber is great for its low latency and longer distance (up to 300 meters), but it is expensive. SFP+ fiber offers low power consumption, but the cost of laying fiber networking everywhere in the data center is prohibitive. The SFP+ fiber electronics can be four to five times more expensive than their copper counterparts, meaning that ongoing active maintenance, typically based on original equipment purchase price, is much more expensive. In addition, replacing a copper connection that is readily available in a server to fiber creates the need to purchase not only the fiber switch port, but also a fiber NIC for the server. EX-SFP-10GE-SR is compatible Juniper SFP+ transceiver that requires a OM3 cable to realize its 10G connectivity, which is an indispensable component for a 10G network.

 

10GBASE-SFP+ DAC—DAC is a lower cost alternative to fiber, but it can only reach 7 meters and it is not backward-compatible with existing GbE switches. Take MA-CBL-TA-1M as an example, it is designed to cover a distance of 1m for 10G connectivity. The DAC cables are much more expensive than structured copper channels, and cannot be field terminated. This makes DAC more expensive than 10GBASE-T. The adoption rate of DAC will be low since it does not have the flexibility and reach of 10GBASE-T.

 

10GBASE-T

The major benefit of 10GBASE-T is that it offers the most flexibility, the lowest cost media, and is backward-compatible with existing 1GbE networks. Like all BASE-T implementations, 10GBASE-T covers a lengths up to 100 meters, which gives network designers a far greater level of flexibility in connecting devices in the data center and the most flexibility in server placement since it will work with existing structured cabling systems. For higher grade cabling plants (category 6A and above), 10GBASE-T operates in low power mode on channels under 30 m. This means a further power savings per port over the longer 100m mode. And because 10GBASE-T is backward-compatible with 1000BASE-T, it can be deployed in existing 1GbE switch infrastructures in data centers that are cabled with CAT6 and CAT6A (or above) cabling, enabling network designers to keep costs down while offering an easy migration path to 10GbE.

 

One challenge with 10GBASE-T is that the early physical layer interface chips (PHYs) consumed too much power for widespread adoption. But there comes a good news with 10GBASE-T is that the PHYs benefit greatly from the latest manufacturing processes. The newer process technologies will reduce both the power and cost of the latest 10GBASE-T PHYs. The latest 10GBASE-T adapters require only 10 W per port. Further improvements will reduce power even more. In 2011, power dropped below 6 W per port, making 10GBASE-T suitable for motherboard integration and high-density switches.

 

Conclusion

Of all the media options offered above, 10GBASE-T breaks through important cost and power consumption barriers in 10GbE deployment as well as its backwards compatibility with 1GbE networks. Deployment on 10GBASE-T will simplify data center infrastructures, making it easier to manage server connectivity while delivering the bandwidth needed for heavily virtualized servers and I/O-intensive applications. I must say, 10GBASE-T will be the best option for 10GbE data center cabling in the near future.

Fiber Optic Cabling Facts: 10 Things You Might Not Know – Part 1

by Fiber-MART.COM

All over the world, people are really beginning to embrace the power and the flexibility of fiber optic cabling. While the technology behind the new fiber optic cabling installations is not exactly brand new, the applications in which it’s being called to use for are and it’s exciting to see. Due to a wide variety of reasons, fiber optic cabling is becoming the fastest, smartest and most flexible way to enable large amounts of digital data to be transmitted and received. The only problem is, many people are still in the dark about fiber optic cabling technology.

 

To attempt to slightly remedy that situation, we’re going to present the first 5 of 10 interesting and exciting about fiber optic cabling today that should shine some “light” on such a great technology. Here are our favorite fiber optic cabling facts:

 

Fiber Optics Has a History – The technology surrounding fiber optics has been around since the 1870’s. The first introduction of actual fiber optic cabling started showing up in the 1950’s. This is a technology rooted in solid history.

 

Fiber Optics Use Light – There is no electrical current being passed through fiber optic cabling, only light. Because of this, there is no heat and no heat means no burning and no fire hazards. During normal use, fiber optics are the safest option for data transmission.

 

Fiber Optics are FAST – Data can be transmitted through fiber optic cabling faster than traditional cabling due to increased capacity. Right now, commercial uses of fiber optic cabling can transmit 10-80 Gigabits per second over just one channel. According to reports, the current record is 15.5 Terabits per second over a distance of 7,000km. To put that into perspective, that’s the equivalent of 10.3 million DSL connections.

 

Fiber Optics Have Many Uses – From the traditional use of data transmission, fiber optics have grown in their use. Now, they are used with gun sights, imaging optics, spectroscopy, supply low levels of power, signs, art and even artificial Christmas trees.

Fiber Optics are Green – The amount of energy required to send a flash of light across a distance in fiber optic cables is far less than that required to send electrical signals. Less power means less carbon output, lower emissions and lower prices.

There is the first half of our 10 favorite facts about fiber optic cabling. As you can already tell, fiber optics are an interesting and exciting development in data transmission technology. Stay tuned for our next installment and the remaining 5 fiber optic cabling facts!

 

To learn more about fiber optic cabling installations and how the technology can help push your company into the next level, please feel free to visit fiber-mart’s Fiber Optic Cabling page.

How to Use Fiber Enclosure in Data Center

by Fiber-MART.COM

Data center fiber optic cabling becomes increasingly difficult and complex due to high fiber count and the special characteristics of optical fiber. During high density cabling, installers should not only consider about the high density and easy-to-manage requirements, but also the requirements for fiber optic cable protection and reliable network performance. A variety of fiber enclosures have been widely used to optimize fiber cabling in data centers or server rooms. Especially for those high density cabling environments, the fiber enclosures are becoming the must-have components. Fiber enclosures come into many types. And their usages are flexible. You can get more than twice the result with half the effort if you know how to make right use and full use of fiber enclosures.

 

Why Do You Need Fiber Enclosure in Data Center?

Fiber enclosure helps to make full used of the spaces in data center by combining most of the fiber optic connections in strong standards modules, providing solid protection of data center links and increasing cabling density. People working in data centers can get easy access to fiber connections and easy cable management. Thus, the cost of data center installation and maintenance can be effectively reduced.

 

The most commonly used fiber enclosure in data center is usually industry standards 1U rack mount fiber enclosure. Now 4U or larger rack mount fiber enclosures are also becoming popular driven by the increasing of fiber counts in data center. Except standards rack mount fiber enclosures, a lot of data centers or server rooms use customized fiber enclosures for their special requirements. The following will take several examples to introduce the applications and usages of the most commonly used standard rack mount fiber enclosures in data centers.

 

Design of Fiber Enclosure in Data Center

For most applications in data center, rack mount type fiber enclosures are used. Generally there are two types (as shown in the following picture) of rack mount enclosures: fiber enclosure with a removable lid and slide-out fiber enclosure. The slide-out version is usually more expensive than the other version. But slide-out fiber enclosure can allow customers to remove the whole enclosure from the rack, thus, it can provide easier internal fiber connection access.

 

The design of fiber enclosure front panel is also very important, which can directly determine how many optical fiber connections a fiber enclosure could provide. The front panel designs of fiber enclosures are also various. There are two most commonly used designs of the fiber enclosure front panels (as shown in the following picture). One is fixed front panel which can be loaded with appropriate fiber optic adapters. The other is removable front pane l that can accommodate several fiber optic adapter panels or cassettes.

 

Three Methods to Use Fiber Enclosures

The using of the fiber enclosure is largely depended on what you insert into the fiber enclosure and which kind of front panel you choose for the fiber enclosure. Here take 1U rack mount fiber enclosure as example to introduce three most popular ways of using fiber enclosures.

 

Fiber Enclosure Using Removable Fiber Adapter Panels

 

The cabling method of fiber enclosure using several removable fiber adapter panels (FAPs) is generally the same as those using fixed adapter panels. It incorporates several FAPs on the front panel. This type of fiber enclosure can provide higher cabling density and more flexible cable management environment. Generally up to 3 FAPs can be installed on a 1U front panel. However, fiber-mart.COM can provide FAPs which is smaller. Up to 4 FAPs can be installed on a 1U front panel with each providing connections up to 24 fibers. 

 

fiber-mart.COM Fiber Enclosure Solutions

If the above mentioned fiber enclosure still cannot satisfy your fiber count requirement, then a larger fiber enclosure up to 2/3/4U or higher fiber enclosure is required. In fiber-mart.COM, a 4U fiber enclosure can provide up to 288 optical fiber connections. Full series of fiber enclosures are provided. The adapter type, port number, fiber type and color of a fiber enclosure and related components can all be customized in fiber-mart.COM. Kindly contact sales@fiber-mart.com for more details.

The True Value Behind Fiber Optic Communications

When it comes to choosing network cables for your business, you want to make sure you choose the right kind. With several different ones available on the market, the last thing you want to do is choose the wrong type and then end up having to replace them all in a few years or even a few months. Fiber optic cables are a preference over copper cables for many IT professionals for a variety of reasons. These are just a few of the reasons fiber optic communications and cables are the better choice and the better overall value:

Why Fiber Optic Communications is a Smart Choice

• The transmission of data is faster. Fiber optic cables are by far the fastest available cables on the market. While they may not be as fast as the speed of light, they are pretty close and nothing else in the market can even compare.
• They maintain more of the signal. Copper wires are notorious for losing some of the signal of the transmission the further the data has to travel. With fiber optic cables, there is a lot less signal loss, or low attenuation, in other words. With fiber cables, data can travel anywhere from 984.2 feet to 24.8 miles but copper cables only allow for 9,328 feet because of their tendency to lose data.
• They are less likely to break. Fiber optic cables are much more durable than copper cables. Fiber cables are made of glass but the copper cable is still more likely to break which means you would have to replace them much more often.
• They do not conduct electricity. This is a huge benefit that many people do not consider. If copper wires and cables are not installed correctly, they can produce electromagnetic currents. These currents can cause a lot of problems with your network and other types of wires. With fiber optic cables, there is no chance of this happening.
• They are not a fire hazard. Because they do not produce electricity and there is no electric current running through them, the light cannot catch fire and your business, as a result, will not be at risk for a loss.

How Does POE Work?

Network cables, such as Cat 5e and Cat 6, comprise eight wires arranged as four twisted pairs. In 10 and 100BASE-T Ethernet, two of these pairs are used for sending information, and these are known as the data pairs. The other two pairs are unused and are referred to as the spare pairs (Gigabit Ethernet uses all four pairs).

 

Because electrical currents flow in a loop, two conductors are required to deliver power over a cable. POE treats each pair as a single conductor, and can use either the two data pairs or the two spare pairs to carry electrical current.

 

Power over Ethernet is injected onto the cable at a voltage between 44 and 57 volts DC, and typically 48 volts is used. This relatively high voltage allows efficient power transfer along the cable, while still being low enough to be regarded as safe.

 

This voltage is safe for users, but it can still damage equipment that has not been designed to receive POE. Therefore, before a POE switch or midspan (known as a PSE, for power sourcing equipment) can enable power to a connected IP camera or other equipment (known as a PD, for powered device), it must perform a signature detection process.

 

Signature detection uses a lower voltage to detect a characteristic signature of IEEE-compatible PDs (a 25kOhm resistance). Once this signature has been detected, the PSE knows that higher voltages can be safely applied.

 

Classification follows the signature detection stage, and is an optional process. If a PD displays a classification signature, it lets the PSE know how much power it requires to operate, as one of three power classes. This means that PSEs with a limited total power budget can allocate it effectively.

 

The differences between power delivered by the PSE and power received by the PD account for power that is lost as heat in the cable. If a PD does not display a signature, it is class 0 and must be allocated the maximum 12.95 watts.

 

POE Plus equipment has a power class of 4. If a regular 802.3af POE source detects this class it will simply enable power as if it was a class 0 device. However, an 802.3at PSE will not only recognise the PD as a POE Plus device, it will also repeat the classification stage, as a signal to the PD that is connected to a power source with full POE Plus power available. (In theory the PD should also be able to request the extra power by communicating across the network link.) POE Plus PSEs can supply up to 30 watts and available device power is 25.5 watts.

 

The final stage after detection and classification of a newly connected device is to enable power: the 48V supply is connected to the cable by the PSE so the PD can operate. Once enabled, the PSE continues to monitor how much electrical current it is delivering to the PD, and will cut the power to the cable if too much, or not enough, power is drawn. This protects the PSE against overload, and ensures that POE is disconnected from the cable if the PD is unplugged.

EDFA – Erbium doped Fiber Amplifier

Related Terms

• Optical Amplifiers
• Optical Communications
• WDM – Wavelength division multiplexing
• Optical Attenuator
• FTTx – Fiber to the x

Definition

Erbium-doped fiber amplifier (EDFA) is the first successful optical amplifier invented by the UK Southampton University and JP Tohoku University. It is one of the greatest invention in optical communication. Erbium-doped optical fiber is incorporated a small amount of a rare earth element erbium (Er) ion. It is the core of the EDFA. From the late 1980s, the EDFA research has been making a major breakthrough continuously. As WDM technology greatly increases the capacity of optical communication, it becomes the most widely used optical amplifier device in the optical fiber communication.

Principle

EDFA is constituted by a period of erbium-doped fiber (about 10-30m) and pump light source. The stimulated emission of erbium-doped fiber under the action of the pump light source (wavelength 980nm or 1480nm), and the radiation of light varies with the change of the input optical signal, which is equivalent to the input optical signal the amplification. Studies have shown that the erbium-doped fiber amplifiers are typically 15-40dB of gain can be obtained, and the distance relay can be increased on the basis of the original more than 100km. So, why did scientists use erbium-doped fiber element to increase the intensity of light? We know that erbium is a kind of rare earth elements, and rare earth elements has its special structural features. Over the years, people have been using the method which doped rare earth elements in optical devices to improve the performance of optics, so this is not an accidental factor. In addition, why is the pump source wavelength chosen from 980nm or 1480nm? In fact, the pumping light source wavelength could be 520 nm, 650nm, 980nm and 1480nm. But the practice has proved that the 1480nm wavelength pumping light source laser efficiency is the highest, followed by the 980nm wavelength.

Advantages

The main advantage of EDFA is a high gain, wide bandwidth, high output power, high pumping efficiency, low insertion loss, and not sensitive to the polarization state.

• Its amplifying area happens to coincide with the minimum loss area of single-mode fiber. This reduces the transmission loss of the light signal which can be transmitted relatively far distance.
• It is transparent to digital signal format and data rate.
• Its amplification bandwidth is so wide that dozens or even hundreds of channels can be transmitted in the same fiber.
• It has low noise figure close to the quantum limit, which means that multiple amplifiers can be cascaded.
• Its gain saturation recovery time is long, and has a very small crosstalk between the respective channels.

 

Applications

When EDFA is used in conventional optical digital communication system applications, we can save a lot of optical repeaters, and the distance relay could also be increased significantly, which is of great significance for the long-haul fiber optic cable trunking systems.

The main applications include:

• It can be used as the light distance amplifier. Traditional electronic fiber optic repeater has many limitations. Such as a digital signal and the analog signal conversion, the repeater should be changed accordingly; repeater changes after the device is changed from a low rate to a high rate; only transmit the same wavelength of the optical signal, and the complex structure, expensive, and so on. Erbium-doped fiber amplifier to overcome these shortcomings, not only do not have to change with the change in the way of the signal, and equipment expansion or for optical wavelength division multiplexing, no need to replace.
•  
• It can be used for the transmitter amplifier and the optical receiver preamplifier. For the rear of the optical transmitter amplifier, the transmit power of the laser is increased from 0dB to +10 db. Optical receiver preamplifier, the sensitivity can also be greatly improved. Therefore, only the line of 1-2 erbium-doped amplifier, the signal transmission distance can be increased to 100-200km. In addition, the erbium-doped fiber amplifier problem to be solved the unique advantages of the erbium-doped fiber amplifier has been recognized by the world, and to be more widely used. However, the erbium-doped fiber amplifier there are also some limitations. For example, in the long-distance communication can not drop channel, each station business contacts is more difficult, not easy to find fault, pumping light source life is not long, as the optical fiber communication technology continues to progress, these problems will be satisfactorily resolved.