Hi everybody!
Today I want to explain EDFA. EDFA is the optical amplifier and if you want to offers our customers CATV (analog and digital cable television), you have to use EDFA.
EDFA is an abbreviation of Erbium-Doped Fiber Amplifier. This amplifier amplifies only optical signal, without any conversion to electric and vice versa.
In the figure below, we can see the EDFA block diagram. This amplifier works on singlemode fiber in the wavelength window 1550nm (1530-1565nm). The main components of EDFA are pump laser (980nm or 1480nm), combiner (WDM coupler) and erbium-doped singlemode fiber with a length of 10-20m.
The optical power of the pump laser is fed to the erbium-doped fiber. This optical power excites the atoms of the erbium-doped fiber to a higher energy level. The typical gain is 15-30 dB and the output power maybe even 20-22dBm.
In the next figure, you can see one example of EDFA.
There are many different models od EDFA.
EDFA may have:
one or two (optical switch) input optical connectors SC/APC or LC/APC,
without or with build-in WDM modul – 4/8/16/32/64/128 input optical ports and 4/8/16/32/64/128 output optical ports. Input optical connectors can be SC/APC, LC/APC, SC/PC or SC/APC. Output optical connectors can be SC/APC or LC/APC. Isolation between CATV and PON min 40dB,
optical test point with SC/APC or LC/APC optical connector,
local and remote connection for configuration (network parameters, optical att) and monitoring (status, alarms),
one or two power supply, …
The typical optical input range is about -10 to +10 dBm. Output optical range depends on gain and from optical splitter (number input and output optical connectors). Max output power is about 22dBm. Dimension of EFDA is from 1 to 3 RU (depends on type and number of optical connectors).
One of the next theme will be optical transmitter and block diagram - interconnections between optical active components and OLT in headends.
Thank you!
