Tag Archives: EDFA

Erbium Doped Fiber Amplifier (EDFA) Used in WDM System

The capacity of fiber optical communication systems has undergone enormous growth during the last few years in response to huge capacity demand for data transmission. With the available wavelength division multiplexing (WDM) equipment, commercial system can transport more than 100 channels over a single fiber. However, increasing the number of channels in such systems will eventually result in the usage of optical signal demultiplexing components with greater values of optical attenuation. Besides, when transmitted over long distances, the optical signal is highly attenuated. Therefore, to restore the optical power budget, it is necessary to implement optical signal amplification. This article may mainly tell you  why EDFA is used in WDM system and how does it work.

Why Use EDFA in WDM System?

EDFA stands for erbium-doped fiber amplifiers, which is an optical amplifier that uses a doped optical fiber as a gain medium to amplify an optical signal. EDFA has large gain bandwidth, which is typically tens of nanometers and thus actually it is enough to amplify data channels with the highest data rates. A single EDFA may be used for simultaneously amplifying many data channels at different wavelengths within the gain region. Before such fiber amplifiers were available, there was no practical method for amplifying all channels between long fiber spans of a fiber-optic link. There are practically two wavelength widows C-Band (1530nm-1560nm) and L-Band (1560nm-1600nm). EDFA can amplify a wide wavelength range (1500nm-1600nm) simultaneously, which just satisfies the DWDM application, hence it is very useful in WDM for amplification.

How Does EDFA Work ?

The basic configuration for incorporating the EDFA in an optical fiber link is shown in the picture below. The signals and pump are combined through a WDM coupler and launched into an erbium-doped fiber (EDF). The amplified output signals can be transmitted through 60-100km before further amplification is required.

Erbium-doped fiber is the core technology of EDFA, which is a conventional silica fiber doped with erbium ions as the gain medium. Erbium ions (Er3+) are having the optical fluorescent properties that are suitable for the optical amplification. When an optical signal such as 1550nm wavelength signal enters the EDFA from input, the signal is combined with a 980nm or 1480nm pump laser through a wavelength division multiplexer device. The input signal and pump laser signal pass through erbium-doped fiber. Here the 1550nm signal is amplified through interaction with doped erbium ions. This can be well understood by the energy level diagram of Er3+ ions given in the following figure.


Where to Buy EDFA for Your WDM System ?

To ensure the required level of amplification over the frequency band used for transmission, it is highly important to choose the optimal configuration of the EDFAs. Before you buy a EDFA, keep in mind that the flatness and the level of the obtained amplification, and the amount of EDFA produced noise are highly dependent on each of the many parameters of the amplifier. Fiberstore provide many kinds of EDFAs, especially the DWDM EDFAs (shown in the picture below), which have many output options (12dBm-35dBm). Besides, they are very professional in optical amplifiers. Whatever doubts you have, they can give a clear reply.


Optical Amplifier Is a Key Technology for Restoring Signals

Optical communications are more and more prevailing for the high demand for telecommunication, video and data transmission. The optical fiber is capable of transmitting many signals over long distance to meet people’s various requirements. But the signals are easily attenuated in the long-distance high speed networks. Amplifiers are a key enabling technology for strengthening optical signals. Electrical amplifiers are originally used but gradually replaced by optical amplifiers.

Optical amplifier is a device that can amplify optical signals directly without the need to convert them into electrical ones. Electrical amplifier is originally used but gradually replaced by optical amplifier. It is a much cheaper solution in comparison with electrical amplifier which has costly conversions from optical to electrical signal. The longer the transmission distance is, the more electrical signals need to be converted, which makes the cost of electrical amplification higher and higher. So optical amplifier is used in an increasing number. More detailed information about it is as followed.

Optical amplifiers can be used as power boosters, in-line amplifiers and detector pre-amplifiers in fiber optical data links. Booster amplifiers are used to increase the optical output of optical transmitters when signals haven’t entered the optical fibers. Once transmitted, the optical signals are attenuated by 0.2dB/km. In-line amplifiers are then used to restore the optical signals to its original power level. At the end of the data link are pre-amplifiers which are used to increase the sensitivity of an optical receiver.

optical ampplifier functions

optical amplifier: functions

There are three most important types of optical amplifiers including erbium-doped fiber amplifier(EDFA), semiconductor optical amplifier (SOA) and Raman amplifier. Here will introduce them briefly.

Erbium-Doped fiber amplifier: it is an optical or IR repeater that amplifies a modulated laser beam directly without optical to electrical conversion. It uses a short length of optical fiber doped with the rare-earth element erbium. The signals-carrying laser beams are usually at IR wavelengths with application of external energy. It has low noise and capable of amplifying many wavelengths simultaneously, which is an excellent choice in optical communications.

Semiconductor optical amplifier: it is an optical amplifier which uses a semiconductor to provide the gain medium. The gain medium is undoped InGaAsP. This material can be tailored to provide optical amplification at wavelengths near 1.3 µm or near 1.5 µm which are important wavelengths for optical communications. It makes fewer noises than EDFA and generates less handle power. But it is more suitable to be used in networks where the best performance is not required for it is less expensive.

Raman amplifier: it is an optical amplifier based on Raman gain created by Raman scattering, which works entirely differently from EDFA or SOA. Raman optical amplifier have two key elements: the pump laser and the directional coupler. The pump laser has a wavelength of 90 nm to 1500 nm. The circulator provides a convenient means of injecting light backwards in to the transmission path with minimal optical loss. Raman amplification occurs throughout the length of transmission fiber, which makes Raman amplifier known as distributed amplifier.

For more information about optical amplifier, please visit www.fs.com.

Low-cost Optical Amplifiers

Communications can be broadly defined as the transfer of information from one point to another. In optical fiber communications, this transfer is achieved by using light as the information carrier. There has become an exponential growth in the deployment and capacity of optical fiber communication technologies and networks over the past twenty-five years.

Optical technology is the dominant carrier of global information. It is also central to the realisation of future networks that will have the capabilities demanded by society. These capabilities include virtually unlimited bandwidth to carry communication services of almost any kind, and full transparency that allows terminal upgrades in capacity and flexible routing of channels. Many of the advances in optical networks have been completed by the advent of the optical amplifier.

In general, optical amplifiers can be divided into two classes: optical fiber amplifiers and semiconductor amplifiers. The former has tended to dominate conventional system applications such as in-line amplification used to compensate for fiber losses. However, due to developments in optical semiconductor fabrication techniques and device design, especially over the last five years, the semiconductor optical amplifier (SOA) is showing great promise for use in evolving optical communication networks. It can be utilised as a typical gain unit but also has many functional applications including an optical switch, modulator and wavelength converter. These functions, where there is no conversion of optical signals into the electrical domain, are required in transparent optical networks.

Low-cost Optical Amplifiers

Cost reduction of optical amplifiers is of increasing concern because of continual pressure on the pricing of optical networking equipment, because of changes in applications and network architectures which are extending the range of applications of amplifiers beyond the line amplifier repeaters of the core network, and because the dominant EDFA technology is not as easily amenable to cost reduction through integration as other technologies such as semiconductors.

Low-cost optical amplifiers will be used in the highest volume, most cost sensitive applications, such as metro and access network line amplifiers, single-channel amplification for high speed, advanced modulation format channels, cable television distribution booster amplifiers(CATV) , and ASE sources for WDM passive optical networks (PONs). The complementary technologies for low-cost amplifiers, such as semiconductor optical amplifiers, and erbium-doped waveguide amplifiers (EDFA), (EDWAs) are covered. EDFAs, which is the dominant technology, comprises multiple components with different features and is based on different technologies.

The challenges and opportunities for reducing the costs of the primary components of EDFAs and the labor costs of assembling EDFAs are discussed, EDWAs offer opportunities for cost reduction by integrating the features of many of the components required for optical amplifiers. However, the lower efficiency of converting pump-to-signal power in erbium-doped planar waveguides compared with erbium-doped fiber, poses an obstacle to the commercial realization of the potential cost advantages of EDWAs, A recent approach is the PLC erbium-doped fiber amplifier, in which many of the passive devices are integrated on a PLC but the gain is provided by an erbium-doped fiber. This approach combines the advantages of PLC integration with the performance and pump efficiency of erbium-doped fiber and is especially advantageous for complex amplifier architectures requiring various optical components.

Fiberstore DWDM optical amplifier modules provide multi-function, low noise, Erbium-Doped Fiber Amplifier (EDFA) solutions that are ideal for metro Dense Wavelength Division Multiplexing (DWDM) applications. This family of C-Band 40 channels optical amplifiers is part of the fiber driver optical multi-service platform solution.