On Which Factors Different Parameters Of EDFA Depends

[Abdullah Baig]

Dear members
I have two Questions
1-I want to inquire on which factors different parameters of EDFA I-e Length of EDFA, Forward Pump Wavelength, Polarization Filter Depends
In my system in am using:
System Bit Rate=13Gbit/s
Optical Fiber Length=50km

For Example: Can i set the length of EDFA 5m for 50km Fiber length. Or EDFA Length is set through some calculation?
2-What is the advantage of using EDFA over simple Optical Amplifier?

Please Find System Snap in Attachement

Attachments:

1. 

   System.png
   

[Damian Marek]

The difference between the two components is the models used. The advantage of the Optical Amp is that you can explicitly state the gain and noise figure and the model is also much more simple. This is great when all you are interested in is a simple gain element. The EDFA lets you set some more specific values and the results. For example the effect of pump power on gain.

Regards

[Ravil]

Hi Abdullah,

According to your last question, I agree with Damian: Optical Amplifier is similar to a “packaged” device (industry version), i.e. you can’t get inside and change it physical parameters; EDFA, on the other side, is similar to “opened” device (laboratory version).
According to your first question, the amplification is exponentially growth with a product of a length of the fiber and its gain coefficient.

[Ravil]

I am pretty sure that you can find this information (as well as the information for your other questions) in two very useful books of G. Agrawal “Fiber Optic Communication Systems” and “Optical Amplifiers”. Unfortunately, I can not upload them for you due to copyright rules…

[Abhishek Shrama]

Hello, Can we change the CORE radius of EDFA for gain flattening???

[Damian Marek]

Yes, core radius, doping radius are both parameters

[Abdullah Baig]

Can we take EDFA Length 5m for 50km Optical Fiber Length.As 5m is Default value?

[Abdullah Baig]

As results are good at 5m EDFA Length.

[Alessandro Festa]

Note that, if you have multiple channels (ie WDM system), the EDFA length will affect the flatness of the channels at its output (different launch power levels into fiber depending on wavelength), while Optical Amplifier is always flat so it is an ideal component

[Abhishek Shrama]

I have also did gain flattening at 9m EDFA length using bidirectional pumping in 128 channel WDM system and it works very good.But variation in edfa length effect the gain flattening

[Abdullah Baig]

I modified the system and simulate it without any amplifier and the results are good with low BER and Q factor=15

I want to inquire:

1-Can i simulate the system without Optical Amplifier or EDFA with Fiber Length =50km

2-On which Fiber Length it becomes necessary to use amplifier?

[Abhishek Shrama]

Ues you can make a system without optical amplifier.But if you want to achieve a long transmission distance then u have to use a amplifier.Because after some distance power of signal degrades.

[Ravil]

Hi Abdullah,

There are several factors needs to be considered to answer your questions about the usage of an optical amplifier and the minimum distance for such a usage. In general, the main factor limiting the transmission is losses (signal decay) in your channel. It mainly defines by attenuation coefficient of the type of optical fiber you have chosen. There are standards for it as well, i.e. ITU-T. The other factor for losses will be the number of connections (separable and in one-piece). For example, according to ITU-T standard for SMF you’ll have 0.25 dB/km.

[Ravil]

The other factor is the total power budget in your channel, i.e. the difference between the power level exiting from your transmitter and the power level entering your receiver. There are also limitations for these to levels of power: nonlinearities (real fiber will always have nonlinear response for high intensity fields) and the sensitivity of your chosen receiver.
You should also keep in mind that the usage of amplifier increases your channel noise, and, hence, reduces your SNR!

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