Timing Jitter in Laser

[Jamal]

Hi all,
Can anyone suggest a way to add jitter in optical pulses ?

[Dr. Dhiman Kakati]

Timing Jitter is one of the unwanted phenomena at the output of the receiver, we should try to avoid pulse broadening.
Regarding you question about “way to add jitter in optical pulses” you can increase the Laser linewidth this will definitely increase the timing jitter. But take care about the Inter symbol interference (ISI).

Regards,
Dhiman

[Jamal]

Thank you Dhiman
Is there any way to add a particular amount of jitter. Like if I want to add 10fs jitter, what should I be doing then ?

[Dr. Dhiman Kakati]

Ok for adding Jitter of your required no. I need to check in optisystem what are the possible option available. I need some more time to respond to you.

Regards,
Dhiman

[Jamal]

Sure Dhiman

[Jamal]

And also can you tell, how to calculate how much the jitter a laser pulse is already producing ?

[Dr. Dhiman Kakati]

Hi Jamal,
Timing jitter is negligible in case of output of a laser, But it is one of the dominant factor at the output of a demodulator, Because of multipath propagation of the different light wavelength as different wavelength has different speed of propagation.
Regarding Jitter calculation in Optisystem there is no such specific tool which will help us to calculate it. I would suugest you to calculate it manually from the eye diagram as shown in the attached picture below:

Regards,
Dhiman

[Jamal]

Okay but when i will convert the output to electrical, there will be photodiode noise also and the eye diagram would not give me only the jitter of laser then right ?
Can I add jitter in the pulses separately ?

[Dr. Dhiman Kakati]

Hi Jamal, Yaa sure you can add jitter by using at electrical part of the circuit by using the component “electrical jitter”,
it calculates jitter from the signal positions with respect to time, Its amplitude is measured in term of “Unit intervals (UI)”, and Unit intervals represents the phase deviation from the period of clock signal, The peak-to-peak UI deviation of the phase function with respect to time is referred as jitter amplitude For how the electrical jitter component work please go through the help sections in the component properties. I think this may be beneficial for you.

Regards,
Dhiman

[Jamal]

Dhiman, how would I add a 100fs jitter for an 8GHz clock using electrical jitter component ?

[SAHIL SINGH]

Hi Jamal,

I agree with the point of view of Dhiman here, It is very correctly mentioned that timing jitter is almost negligible when we consider the case of output of a laser, but one definitely needs to take into account that it is one of the dominant factor at the output of a demodulator, because of multipath propagation of the different light wavelength as different wavelength has different speed of propagation… Thanks Dhiman for the nice explanation of the concept..

Regards
Sahil Singh

[Dr. Dhiman Kakati]

You are most welcome sahil.

regards,
Dhiman

[Jamal]

Dhiman and Sahil thank you for the guidance.
Dhiman thank you for telling about the electrical jitter, but I was wondering if there was any way we could add jitter via some phase noise in a laser pulse

I have actually made a multiple wavelength laser source and now I am trying to find its jitter following your method. Can you see if I am doing it right. I am attaching the setup also

[Dr. Dhiman Kakati]

Hi Jamal,
I am Unable to open your design file showing some error. “unable to load document from storage”. I need help from you regarding this. I am using Optisystem V13. Thanking you.

Regards,
Dhiman

[Rajguru M. Mohan]

Hi Jamal,
I would suggest you to please visit following links for Timing jitter in LASER. As Timing jitter is related
to phase noise in the optical frequency components of the incoming pulse train.
The relevant jitter can be that between data-carrying pulses and a clock signal
In the absence of any technical noise, the jitter of a mode-locked laser
is limited by quantum noise, but in most cases it is dominated by vibrations and drifts of the laser resonator.

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=135313&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel1%2F3%2F3684%2F00135313.pdf%3Farnumber%3D135313
http://inspirehep.net/record/824106/files/fermilab-conf-09-191.pdf
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-18-5-5041

Hope this will help you

[Rajguru M. Mohan]

Hi Jamal,
As we know Jitter is defined as the short-term variations of a digital signal’s
significant instants from their ideal positions in time
Although Aligant technologies has device 81134A with which it is easy to
add jitter to any kind of data or clock signal. This is very
useful if you need to test the jitter tolerance of your circuit
designs, e.g. data receivers or clock recovery circuits, allows you to measure and
characterize the jitter that disturbs your signals.

We have Electrical Jitter which Inserts jitter in the input signal in optisystem,
for design go through link:

Signal degradation – Jitter

We could measure jitter in optisystem using Eye and BER Analyzer: Eye diagrams with color grades and histogram analysis in user defined regions. Includes user defined FEC gain curve, jitter measurements, and eye masks in accordance with Agilent standard file format.
Thanks

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