chirp profile

[muhammad jawad]

Dear Friends
hope you all will be fine

I am attaching a picture of the chirp shape(which is up-chirp i.e increasing along the pulse like a slope in RED COLOR).I am getting chirp in CW probe by exploiting XPM in HNLF by data modulated gaussian pulsed signal.I want to change the existing chirp shape to a sine wave like shape or some other shape except which is in attachment.Plz tell me how to vary the chirp shape.

regards

[Mohamed A. A. Abouseif]

The Chirp of the input pulse can defined as linear or measured. when it is defined as a measured chirp, there are two parameters you have to enter alpha and adiabatic. these two parameters change the phase of the input signal with time as a function of the input power. this equation is written in the optical pulse generators manual.

hope that help,
Mohamed Abouseif

[muhammad jawad]

Dear Mohammad AbouSeif
Thanks for your reply
But i am not talking about the chirp parameter in a source.I am specific when in an unchirped pulse,the chirp is produced in CW light signal by PM modulation.How to vary its shape????

[Aadil Raza]

@ Mohammed A.A Abouseif

As you said “alpha and adiabatic can change the phase of the input signal with time as a function of the input power”

Can we change the phase of input RF signal, modulated with optical carrier using MZM, with time as a function of the input power???

Regards

[Mohamed A. A. Abouseif]

RF signal is not pulse so, but what I am talking about is the optical pulse. so the chirp would be across the pulse internal time or in other words the instantaneous frequency of the pulse. But if you have CW RF signal and its phase is changing with time depending on its power so you make the signal to be modulated by itself!!

[Mohamed A. A. Abouseif]

Mohamed Jawad,
It is the output of a system, do you want to force it to some shape?
you can export data outside and treat it externally!

thanks
Mohamed Abouseif

[Aadil Raza]

Yes I want to have change in Phase of RF modulated signal (as a function of CW laser power) at the output of system just by utilizing self-phase modulation in highly nonlinear fiber.

Theoretically there is a relationship for nonlinear phase shift as a function of intensity/power of laser but How can we do this in optisystem?

Yes I want to force it to have some different phases but want to do it all optical processing not externally..

[muhammad jawad]

Dear Aadil
The phase change or phase mod like SPM or XPM is dependent on many factors like non-linear length,intensity etc.so you may change the degree of SPM or XPM by varying the pump/signal intensity as per your wish.Be clear that as a result of PM,your CW carrier will be modulated and the pulses experience chirp as a result of SPM/XPM
regards
we may have detail discussion over phone as well

[Mohamed A. A. Abouseif]

Aadil,
yes as Jawad explained SPM and XPM are dependent on many factors.
Be clear that SPM (self phase modulation ) means that the wave will experience a phase change due to its intensity while XPM (cross phase modulation) means that the pulse experience a phase modulation due to other signal intensity. since you do not have other signal so there is no XPM you only have SPM.
if you explain more about your idea we can discuss more.

thanks
Mohamed Abouseif

[Aadil Raza]

Dear abuseif

I just want to simulate the system in Optisystem. I want to see how much change in phase of RF signal can be achieved just by changing laser power using HNLF.

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