average soliton regime

[Abu Bakar]

Hi, Everyone I have a question that in optical fiber average soliton regime why multiple pulses instead of single pulse. What is the reason behind that?? Please tell me??

[Mohamed A. A. Abouseif]

Hi Abu Bakar
In principle, multiple pulses are generated as a result of accumulated nonlinear phase shift (phi_NL). if the value of Phi_NL exceeds certain value based on the system design, multipulsing start to appear instead of single pulse. you can see that in simple simulation using OptiSystem. just put the input as a soliton pulse then design the optical fiber as a medium of propagation with certain length and nonlinear coefficient so that you can see the pulse splitting in the output port of the fiber.

thanks
Mohamed Abouseif

[Abu Bakar]

ok thanks Mohamed Abouseif. What is the value of Phi_NL exceeds certain value based on the system design?? I am little bit confuse please give more explanation. Kindly clear me.

[Abu Bakar]

Here i upload my simulation model pic and also receiver anfd transmitter result. what is your observetion says about multiple pulses??. please reply me.

Attachments:

1. 

   r1.png
   

2. 

   r2.png
   

[Mohamed A. A. Abouseif]

Hi,
nonlinear phase shift is equal gamma*peak power*length. first intuition, you have around 100 km of HNLF (gamma is not clear)
you can calculate gamma = 2*pi*n2/(lambda*Aeff) then you can calculate the peak power of the input pulse then the accumulated phase shift.
based on the literature and the system design the multi-pulsing appears if this value exceeds certain value might be pi or less based on the nature of the fibers.

hope that helps,
thanks
Mohamed Abouseif

[Abu Bakar]

ok Thanks. My another question is that I use two DCF one use at the start and one use at the end. The equation of DCF is D1L1+D2L2=0 But in my case this equation becomes D1L1+D2L2+D3L3=0. Because i use two DCF. SO in my case i could not satisfy this equation according to setting my parameter. If i set my paratmeter according to this equation then my BER and Q factor decreases and not good result and not get such type of good solitonic pulse.Also i want to say that the to make solitonic pulse the condition min. dispersion is present not completely zero dispersion. I set all the parameter by hit and trail method so i get good solitonic pulse and get more BER and Q factor. So In short i say that if i put my values which i use in this equation then i cannot get 0 answer which is good which means that dispersion compensate not completely zero which is good. So tell me i am right or wrong??

[Mohamed A. A. Abouseif]

Hi,
I think it is better to have a documented published results and then start to verify it. yes soliton propagation need balance between nonlinearity and dispersion (not zero dispersion).

thanks
Mohamed Abouseif

[Abu Bakar]

ok thanks

[Abu Bakar]

In highly non linear fiber the parameter dsispersion value use is -1.7?? Is it true??

[Mohamed A. A. Abouseif]

It varies from fiber to another and it is wavelength-dependent value. check the data sheet for the fiber or ask the vendor. if just for simulation, check it in the literature for the specific application.

thanks
Mohamed Abouseif

[Abu Bakar]

ok thanks.

[Abu Bakar]

For optical soliton min dispersion is required so can you tell the value of dispersion that how much min dispersion ??? and also tell that this dispersion is chromatic dispersion or group velocity dispersion??

[Mohamed A. A. Abouseif]

there are many values and many designs for soliton. please read chapter 5 in “Nonlinear fiber optic”, G.P. Agrawal. you will find many examples that you can start with.

thanks
Mohamed Abouseif

[Abu Bakar]

Please guide me how to make a mathematical model according to my simmulation model? I have not find any material which help me. Please reply me as soon as possible

[Mohamed A. A. Abouseif]

what do you mean by mathematical model? all the equations describe the propagation of pulse through optical fiber exist in many literature and mainly Agrawal book!

[Abu Bakar]

I mean to say that non linear Schrodinger equation is derived already So i make my model on optisystem and with respect to my optisystem model i have changes in non linear schrodinger equation and simplify them. So I changes in non linear schrodinger equation according to my model so my queation is where integration or derivation should apply in my equation i don’t understand this thing. e:g in agrwal book their is present Split Step method to solve the equation and simplify them.

[Abu Bakar]

In dispersion formula D=2*pi*c/lamda*beta2 . in his formula what is c represents?? if c is constant which type of constant??

[Abu Bakar]

in dispersion formula D=2*pi*c/lamda*beta2 . what is c represent? if constants then what type of constants what is the value of c? kindly reply me?

[Mohamed A. A. Abouseif]

Abu Bakar,
c is the speed of light = 3*10^8 m/sec

thanks
Mohamed Abouseif

[Abu Bakar]

when we find the one value of one complete cycle of pulse after that when we find bit slot of pulse why we divide cycle value by 2? Also define soliton period?

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