why different gains

[umer syed]

hello everyone
I am working on the development of EDFA in L Band for gain flatness optimizing the fiber length and pump power, But I see that
gain is not same for multiple source and single source at same wavelength, meaning that for example I got 30 dB gain for single
source input at 1600 nm , but I got only 22 dB for multiple source input at the same wavelength. What would be the reason for this ?
with regards

[aasif bashir dar]

hi umar syed
I think the total gain should be the same, if the total input powers are the same for both cases.
Did the power of your single carrier match the total power of your multiple carriers combined?
If not, you may have seen gain saturation…

Did you do simulations or experiments?
If simulations, are all your carriers modeled as CW sources (without linewidth), or did you consider them to have a certain bandwidth?

Hope that helps somewhat, with reagards

[umer syed]

hi aasif bashir
the total power is same but the gain is different…i have done the simulations but
i am not aware about the concept of linewidth which u are talking about…

can u also please tell me what should b the the maximum gain for an optical amplifier in an optical systems.

with regards

[ZULKARNAIN]

hi umer syed…
i totally agree with aasif bashir dar that the total gain should be same.
As far as gain of the EDFA depends on many parameters such as EDF length, pump power, operating wavelength etc. EDFA gives different gain at different wavelength because of strak split in the energy band of EDF which led emission at range of wavelengths (C-band or L-band).  Gain is relatively flat in L-band compare to C-band, however, value of gain is higher in C-band compare to L-band.
hope your problem gets solved
with regards

[umer syed]

hi aasif bashir..
I think that maximum gain for the optical amplifier is determined  by  ASE threshold which depends  in particular  from  flurescence
life time and  backward  light  Relaigh scattering. Quntitative eveluation of the similar  task have been solved repeatedly  for
powerfull  laser system  for  laser initiated nuclear reaction. Also, it will depend on the position of the amplifier as well as
the number of channels loaded into it. The most common is optical gain of 20-30 dB, but it may be reduced by increasing the input power..
Am i in the right direction…
with regards

[FAYIQA NAQSHBANDI]

HELLO UMER SYED..

I also agree with aasif bashir dar here that the total gain should be same…As far as gain of the EDFA depends on many parameters such as EDF length, pump power, operating wavelength etc. EDFA gives different gain at different wavelength because of strak split in the energy band of EDF which led emission at range of wavelengths (C-band or L-band)…
Gain is relatively flat in L-band compare to C-band, however, value of gain is higher in C-band compare to L-band… I hope it will help you.

thanks & regards

[ZULKARNAIN]

hello fayiqa naqshbandi…
well the answer was already given to the question.
with regards

[Atul Sharma]

Hi Umer Syed. Greetings from my side.

Actually I did not get your query at first but with what Aasif Bashir Dar explained i got what your query was at first place. I agree with him saying that the total gain should be same.
As far as gain of the EDFA depends on many parameters such as EDF length, pump power, operating wavelength etc. EDFA gives different gain at different wavelength because of strak split in the energy band of EDF which led emission at range of wavelengths (C-band or L-band). Gain is relatively flat in L-band compare to C-band, however, value of gain is higher in C-band compare to L-band.

Regards
Atul Sharma

[umer syed]

hi zulkarnain
thanks for your explaination…can u please explain me why the gain is higher in C-band compare to L-band.Gain is not same for
multiple source and single source at same wavelength…..
hope you understand my question
with regards

[ZULKARNAIN]

hi umer syed..
you are welcome
with regards

[aasif bashir dar]

you are welcome umar syed, greetuings and cheers

[SAHIL SINGH]

Hi Umer Syed,

I totally agree with aasif Bashir that the overall gain of the system should be same… Whereas the gain of EDFA depends on length of fiber and wavelength in particular…Also as mentioned by Atul Sharma EDFA gives different gain at different wavelengths…

Regards
Sahil Singh

[aasif bashir dar]

hi umar syed,

as mentioned by alll, gennerally we use EDFA as the main amplifier along the fiber link..but the gain of EDFA depends on both length of fiber and wavelength in particular..
use of raman amlifier (which has nearly equall gain for all wavelength)is usually restricted to the rx end, but it amplifiers the signal by large amont can cause fiber non-linearities ,if used before fiber.

wirh regaerds

[Atul Sharma]

Thanks Aasif dar for sharing an extra bit of knowledge.

[burhan num mina llah]

Hi umer syed

Very well explained by aasif bashir dar.. Aasif will you please specify or i would say explain a bit more about the difference in gain in the two different bands respectively L and C band as is already asked by umer syed.. That would be helpful for all of us as there might be a genuine reason for this difference of gain for sure. I intute that there should be a reason for different gains in two different bands.. Please provide the response

Regards

Burhan

[umer syed]

thanks everyone for your efforts
with regards

[Atul Sharma]

you are welcome Umer 🙂

Regards
Atul Sharma

[SAHIL SINGH]

Hi Umer syed,

It is a very interesting question raised by atul sharma that how are you implementing this back up fiber in optisystem ? I too am eager for your response.. Hope to hear from you soon

Regards
Sahil Singh

[Atul Sharma]

Looking forward for the response from Umer Syed.

[Aabid Baba]

Hello Umer Syed,
The above mentioned posts have clearly given you an idea about different perspectives now. I hope it will help.
Regards

[Ranjeet Kumar]

Hi Umer,
Could you please explain the terms Single source and multiple source in your design.
What does it mean in optisystem.
Seeking your response.

[SAHIL SINGH]

Hi Ranjeet,

Infact a very nice question posed by you about Single source and multiple source.. Hope to hear from umer syed…

Regards
Sahil Singh

[Naazira Badar]

Hi burhan num mina llah..
Well I think since the gain is wavelength dependent, so it would certainly be different in different bands like C and L ..because they operate on different wavelengths.

Regards
Naazira Badar.

[Atul Sharma]

Hello Naazira Badar. Greetings from my side.

I want to ask here that how gain is wavelength dependent here? It is really an interesting point to know. Shall look forward to hear from you soon.

With regards
Atul Sharma

[burhan num mina llah]

Hi Naazira badar

thanks for the information that is ofcourse the reason… here i guess its in the same band but the problem is between the number of sources whether it is single and multiple and likewise does the gain differ..

Regards

Burhan

[burhan num mina llah]

Hi Ranjeet

I believe what umer syed is referring to hear is that we have single source as for example CW laser and as multiple sources we have an array of CW laser or we can say WDM Transmitter containing multiple sources…

Regards

Burhan

[Atul Sharma]

hi Burhan Num mina Llah. Greetings from my side.

I feel you are right in saying that here Umer Syed refers to single source as for example CW laser and as multiple sources as for an array of CW laser. Thanks for replying here and sharing it.

With regards
Atul Sharma

[Naazira Badar]

I understand that Burhan num mina llah..but even if we use the same band, but multiple sources, we use the different wavelengths. so i think the same logic should apply.

best wishes
Naazira Badar.

[burhan num mina llah]

Hi Naazira Badar

yeah that could be the reason for sure… different gains for different wavelength..but here as you can take a look at the query posted again that he has mentioned that at the same wavelength.. does it still happen on same wavelength..??

Regards

Burhan

[Naazira Badar]

Hi Burhan num mina llah.. and Hi Umer syed..

I am presuming that by multiple sources, you mean multiple CW LASERS.. but I don’t understand why would you transmit using the same wavelength from all the sources at the same time?! This would result in wavelength interference…and that could be a reason that at the EDFA output, different gain is achieved than in single source case. Please correct me if I have understood the query or the concept wrongly.

Best Wishes
Naazira Badar.

[SAHIL SINGH]

Hi Naazira,

I too agree with your view that when you transmit using the same wavelength from all the sources at the same time that would definitely lead to wavelength interference.. Very well pointed out..

Regards
Sahil Singh

[Author]

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