EDFA – Amplificateur à fibre dopée à l’erbium

 Definition

Erbium-doped fiber amplifier (EDFA) is the first profitable optical amplifier invented via the UK Southampton University and JP Tohoku University. It is one of the biggest invention in optical communication. Erbium-doped optical fiber is integrated a small quantity of a uncommon earth aspect erbium (Er) ion. It is the core of the EDFA. From the late 1980s, the EDFA lookup has been making a most important step forward continuously. As WDM science radically will increase the ability of optical communication, it will become the most broadly used optical amplifier machine in the optical fiber communication.



Principle
EDFA is constituted through a duration of erbium-doped fiber (about 10-30m) and pump mild source. The encouraged emission of erbium-doped fiber below the motion of the pump mild supply (wavelength 980nm or 1480nm), and the radiation of mild varies with the exchange of the enter optical signal, which is equal to the enter optical sign the amplification. Studies have proven that the erbium-doped fiber amplifiers are usually 15-40dB of obtain can be obtained, and the distance relay can be accelerated on the foundation of the authentic extra than 100km. So, why did scientists use erbium-doped fiber factor to amplify the depth of light? We recognize that erbium is a form of uncommon earth elements, and uncommon earth factors has its specific structural features. Over the years, humans have been the usage of the approach which doped uncommon earth factors in optical units to enhance the overall performance of optics, so this is no longer an unintentional factor. In addition, why is the pump supply wavelength chosen from 980nm or 1480nm? In fact, the pumping mild supply wavelength may want to be 520 nm, 650nm, 980nm and 1480nm. But the exercise has proved that the 1480nm wavelength pumping mild supply laser effectivity is the highest, observed through the 980nm wavelength.



Advantages
The essential benefit of EDFA is a excessive gain, huge bandwidth, excessive output power, excessive pumping efficiency, low insertion loss, and now not touchy to the polarization state.

Its amplifying region happens to coincide with the minimal loss vicinity of single-mode fiber. This reduces the transmission loss of the mild sign which can be transmitted enormously some distance distance.
It is obvious to digital sign layout and information rate.
Its amplification bandwidth is so vast that dozens or even thousands of channels can be transmitted in the equal fiber.
It has low noise determine shut to the quantum limit, which skill that a couple of amplifiers can be cascaded.
Its reap saturation restoration time is long, and has a very small crosstalk between the respective channels.

Applications
When EDFA is used in traditional optical digital verbal exchange gadget applications, we can store a lot of optical repeaters, and the distance relay should additionally be elevated significantly, which is of exceptional importance for the long-haul fiber optic cable trunking systems.

The fundamental functions include:

It can be used as the mild distance amplifier. Traditional digital fiber optic repeater has many limitations. Such as a digital sign and the analog sign conversion, the repeater have to be modified accordingly; repeater adjustments after the machine is modified from a low fee to a excessive rate; solely transmit the equal wavelength of the optical signal, and the complicated structure, expensive, and so on. Erbium-doped fiber amplifier to overcome these shortcomings, now not solely do now not have to alternate with the exchange in the way of the signal, and tools growth or for optical wavelength division multiplexing, no want 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 energy of the laser is extended from 0dB to +10 db. Optical receiver preamplifier, the sensitivity can additionally be appreciably improved. Therefore, solely the line of 1-2 erbium-doped amplifier, the sign transmission distance can be accelerated to 100-200km. In addition, the erbium-doped fiber amplifier trouble to be solved the special blessings of the erbium-doped fiber amplifier has been diagnosed by way of the world, and to be greater extensively used. However, the erbium-doped fiber amplifier there are additionally some limitations. For example, in the long-distance verbal exchange can now not drop channel, every station commercial enterprise contacts is extra difficult, now not handy to discover fault, pumping mild supply lifestyles is now not long, as the optical fiber verbal exchange technological know-how continues to progress, these troubles will be satisfactorily resolved.