Learn about EDFA equipment in few minutes

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by http://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.

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