FWM in erbium doped fiber

[Abhishek Shrama]

I am working on FWM in EDF.I wanted to know whether FWM generate in erbium doped fiber or not.is there any effect of data rate on FWM.Because i have did litrature survey and found there is no effect of data rate.But in my system i observe the effect of bit rate on FWM.When i kept BW of MUX and DEMUX 10Ghz then no effect observed.When i change the BW of MUX/DEMUX it effect the FWM.
Why power spectrum with increase in data rate contracts?????

[Dr Rk Sethi]

Abhishek Shrama Hi,
Erbium Doped Fiber Amplifiers were initially developed to replace SONET / SDH optical to electrical to optical (O-E-O) regenerators.
EDFAs cam amplify any optical signal in their operating range, regardless of the modulated bit rate. it provides efficient wideband amplification for the C-band. In case of multi-wavelength signals, so long as the EDFAs has enough pump energy available to it, it can amplify as many optical signal as can be multiplexed into its amplification band.
Regards.

[Alessandro Festa]

Hi Shrama, if by FWM you mean Four Wave Mixing, yes it can happen in EDFAs. If the active fiber is long enough and input signals are high and with tight spacing, fwm can happens as it happens in transmission fiber.

[Abhishek Shrama]

Thank you Rk sethi and alessandro. Can you please attach a file in which FWM generate in erbium doped fiber?Sethi sir i want to know why optical power spectrum compress when we increase bit rate??

[Alessandro Festa]

I don’t have such file, but you can try to generate it by using a very long length (20 meters?)and closely space input channels. Let me know if my answer helps.

[Ravil]

Hi Alessandro, I am just curious about the answer you gave about “using a very long length”. Did you mean that 20 m is a sufficient distance to observe FWM effect in EDFA? What powers should we use for that?

[Alessandro Festa]

Hi Ravil,
it does really depend on number of channels/spacing/power of the EDFA. But from my experience, when you use erbium fiber with low doping concentration (which means that you need a longer piece of fiber to reach the same gain) you are exposed to the FWM problem inside the edfa itself.
Does this reply to your question?

[Ravil]

Hi Alessandro,

I understood your point. If I am recalling it correctly, all the range of parameters you have named (number of channels, spacing, power of the EDFA) affects fiber with the increment in its length. Thank you for your clarification!

[Abhishek Shrama]

yeah ravil!! in erbium doped fiber I have already tried it with even longer lengths (upto 1000 m) with very low channel spacing and all the parameters set to excite FWM but no results. It majorly depends upon the parameters of dispersion and non liner index of fiber. but in edf we dont have these parameters to vary. so it is not possible to observe FWM in Erbium doped fiber only. we have to use smf along with it . even pumping the signal doesnot give any results

[Alessandro Festa]

This means EDF is not taking into account nonlinear propagation effects. What about using the Optical Fiber Amplifier component?

[Abhishek Shrama]

I need to do it in erbium doped fiber.

[Alessandro Festa]

Ok, so I guess it is impossible for you to stimulate FWM effect…you can try to ask Optiwave team if they plan to add this feature on future releases.

[Damian Marek]

Hi Abhishek,

I think I suggested to you or someone else to use the optical fiber amplifier. I know this is not optimal but what you could do is use the ER-doped fiber, put all of your parameters in and measure the gain profile. You could then import this gain profile into the optical fiber amplifier and simulate the nonlinear effects. This should give an accurate model of what is happening, unless of course the nonlinear effects change the pump and signal interaction considerably.

Regards

[Abhishek Shrama]

thanku damian.. i will try and respond if required

[Abhishek Shrama]

HELLO ALESSANDRO,I have tried it long time ago using high pump powers,different pumping techniques and using ultra narrow channel spacing,but could not get FWM in erbium doped fiber alone.However FWM in hybrid system where first i put smf and then edf.
I want to change a non linear effect of erbium fiber in order to increase the non linearity,but there is no option to make it work like as i i want.Is there any solution???

[Alessandro Festa]

Have you tried using “Optical Fiber Amplifier” component? It has a tab for nonlinearities, try to change n2

[Abhishek Shrama]

Hi Alessandro ,can you please attach a screen shot where n2 is? because i did lot of study on it,but there is no n2 in any option in erbium fiber

[Abhishek Shrama]

Hi RK SETHi,As i mentioned in topic that i am working on FWM erium doped fiber,not on EDFA amplifier.Can you please tell me how to increase its non linear cofficiet.As in Erbium doped fiber in optisystem does not have option to change this.Also there are files from optifiber software on which it works.Please suggest me the changes or provide me the .dat file with high non linear index ,so that i can observe the effects of FWM..Tell me if i can change dispersion of erbium doped fiber from optisystem.

[Dr Rk Sethi]

Abhishek Shrama Hi,
As you mentioned that you are working on FWM erbium doped fiber, Can you please tell me exactly what is your research objective? Are you following some reference paper? Four-wave mixing is a nonlinear effect. It takes place when two waves of different wavelengths are injected into an SOA, resulting in to a new optical field with new frequency is generated at the output. can you please attach a screen shot of the compressed optical power spectrum when bit rate increases?

[Abhishek Shrama]

HI RK SETHI,As all we know FWM generate due to nonlinear effects in SOA ,SMF and DCF. But i want to observe the effect of FWM in erbium doped fiber alone.I dont want to observe any HYBRID effect i.e SMF+EDF.I want to analyze effects only in erbium doped fiber.We know EDF is also a fiber ,only difference is of er3+ ions doping .So if we observe FWM in SMF DCF then also there are effect in EDF.That is my objective.
I am attaching a Spectrum analyzer at different bit rates.I found when we increase data rate spectrum gets contract,i want to know why this happens??

I have used same setup for 1G and 40 G system,but why spectrum contracts.
Hope ypu understand my objective

[Dr Rk Sethi]

Abhishek Shrama Hi,
The X – axis parameters are not readable in the attached plots.

[Alessandro Festa]

I cannot read X-parameters on your images too. Can you post them with higher resolution?

[Ashu verma]

Hi Abhishek ,you can use pump with erbium fiber as more power input in EDF ,more nonlinear effects induce.You can use high pump powers,different pumping techniques.In EDF alone FWM is difficult to generate.In EDF there is no option to delect or change the Dispersion.As we kvow as disperion decrease FWM increse.But either you use optifiber to include these effects.

[Abhishek Shrama]

Thank you Sam sung.

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