Optical Output Power Of Laser Emission

[ZULKARNAIN]

i am currently studying the nature of output of a laser by varying certain parameters of the input signal,discussed in my previous post also.The bit rate is 1Gbps,but the eye diagram is not good as the marks and space are not clear.Also the bias current is 10mA.Can anyone please explain how to improve the distiction between marks and space.
Also attaching the snapshot of the eye diagram.
with regards.

[Aabid Baba]

Hello Zulkarnain,
Though you are working on a low data rate and yet your eye diagram is not proper. Its strange. Could you please upload your .osd file because that way it would be more convenient to analyze what exactly you are doing. Can you detail about your other parameters that you are using for the transmission. Better would be to upload the .osd file so that people will help you accordingly. i Hope to se your problem get resolved soon.
Regards

[ZULKARNAIN]

hi aabid baba..
thank you for showing concern..
actually i am studying the output of a laser by changing bit rate and input bias current. At this current i.e.10mA when i am changing the bit rate to higher rates the eye diagram is getting worse and there is no distinction between marks and spaces.Also the BER is very high and quality factor is also very low.
Hope you will find some find to respond to my query.
with regards

[Aabid Baba]

you are welcome zulkarnain. Sure

[Ubaid Bhat]

hi zulkarnain..
you have said that you are varying the bit rate keeping the bias current constant because of which your eye diagram is not good.well i think you should also try to increase the bias current and keeping the bit rate fixed to see the effect of bias current on bit rate.may be your results might get better.
hope this solution works
with regards
ubaid bhat.

[Atul Sharma]

Hello Zulkarnain. Greetings.

I agree with Aabid.

[Aabid Baba]

welcome.

[aasif bashir dar]

hi zulkarnmain,

you are taking about the the nature of output of a laser with 1Gbps and the bias current of 10mA…. but you have not mentioned the type of laser component you are using….

we have the parameter called as the extinction ratio…that defines the ratio of power strengths in between the mmark and spsce

with regrads

[ZULKARNAIN]

hi aasif bashir dar…
thank you for replying my query.yes i know about extinction ratio which the power strengths in between marks and spaces.since the marks amd spaces are not distinguishable so we can not define the extinction ratio for the current eye diagram.
well i am using a CW Laser with frequency f=193.099THz, Ith = 33.45mA, Tsp = 1ns, Tph = 3ps.
with regards

[aasif bashir dar]

hi zulkarnain,

i got confused by your reply…what software are you using..( frequency f=193.099THz, Ith = 33.45mA, Tsp = 1ns, Tph = 3ps.)are the parameters that you are talking of you have set for CW laser…
but there is no such options to set parameters in optisystem.. apart from the frequency we can set power, line width , initial phase as the main parameters of the CW laser in the optisystem

with regards

[ZULKARNAIN]

hi aasif bashir dar…
thankyou for showing concern.
frequency is set for the pseudo random bit sequence generator and not cw laser.
with regards

[ZULKARNAIN]

for cw laser we are changing the bias current to study the effect of bias current on eye opening and closing.well actually at the current bias current current and bit rate the marks and spaces are not distinguishable.Also when i increase the bit rate the quality factor is further reduced.
with regards

[aasif bashir dar]

hi zulkarnain,

i asked you about the software you are using to view to study the effect of bias current on eye opening and closing…

there is no provision of setting bias current for CW lasers in the optisystem….

morover frequency can be set in CW laser… for pseudo random bit sequence generator we can not set frequency… hence your reply #34468 is wrong…

with regards

[ZULKARNAIN]

hi aasif bashir dar…
sorry i mistakenly wrote sequence generator in place of cw laser.
sir could you please tell me then how can i improve my eye diagram.
with regards

[Ankita Sharma]

hi..
I agree with aabid and aasif that hough you are working on a low data rate and yet your eye diagram is not proper. Its strange. Could you please upload your .osd file because that way it would be more convenient to analyze what exactly you are doing. Can you detail about your other parameters that you are using for the transmission. Better would be to upload the .osd file so that people will help you accordingly. i Hope to se your problem get resolved soon.
Regards

[Aabid Baba]

Hello Ankita,
what do other parameters refer to?

[umer syed]

hi zulkarnain…
Based on your result, in my opinion, it looks like a timing jitter might be the reason of such a gap. Do you have this gap when you are transmitting your signal for short distances? Jitter grows cubically with the distance.
with regards

[ZULKARNAIN]

hi umer syed…
thank you for showing concern for my query.
well i not able to understand your point about the gap.could you please elaborate over this.
Actually i am unable to get the gap between marks and spaces in the eye diagram. Hope you got my point.
with regards

[ZULKARNAIN]

hi umer syed…
well in my project i was trying to vary the bit rate to see the effect on the eye diagram,but it got worse with increasing bit rate.also the quality factor is very low.now i think i will change the power as well as reduce the length of the fiber to see the effect of these parameters.i hope that with increase in power and for shorter distances the eye diagram should improve.
i hope you will supervise me in this project for the study of various other parameters as i am new to optiwave.
with regards.

[Atul Sharma]

Hi Zulkarnain. Greetings.

It is natural if you tend to increase the data rate there are other repercussions in form of degradation of other parameters. So i believe you need to keep in mind the different tradeoffs between different parameters.

Regards
Atul Sharma

[ZULKARNAIN]

HI ATUL SHARMA..
thanks and greetings for responding to my query..
yes it is true that there is always trade off between various parameters and we have to choose optimum values for various parameters so that we get optimum results.that is we can can not incraese the gain too high because of that degradation will occur.
with regards

[Atul Sharma]

Hello Zulkarnain. Greetings.

Well i thought of mentioning it because there is a definite trade off between various parameters that you need to keep in mind while designing a system. I hope you understand my point.

Regards
Atul Sharma

[SAHIL SINGH]

Hi Zulkarnain…

I agree with atul sharma that if you tend to increase the data rate there are other repercussions in form of degradation of other parameters.Also tradeoff between various parameters must be understood for the system design to be effective..

Regards
Sahil Singh

[ZULKARNAIN]

hi sahil singh…
very much thanks for replying to my query…
i also agree with you also that if we tend to increase the data rate there are other repercussions in form of degradation of other parameters.Also tradeoff between various parameters must be understood for the system design to be effective.
with regards

[Atul Sharma]

Hello Sahil Singh. Thanks.

I thought it was worth mentioning here.
Regards
Atul Sharma

[SAHIL SINGH]

Hi Zulqarnain,

You are welcome.. hope your query gets resolved…

Regards
Sahil Singh

[Ranjeet Kumar]

Hi Zulqarnain,
We have different phase to analyse the complete lasers characteristics.
For est methods for the spectral characteristics of lasers , i would suggest you to visit this link:
https://www.iso.org/obp/ui/#iso:std:iso:13695:ed-1:v1:en
For Vocabulary and general properties:
https://www.iso.org/obp/ui/#iso:std:iso:14880:-1:ed-2:v1:en
For Test methods for laser-induced damage threshold — Part 1: Definitions and general principles:
https://www.iso.org/obp/ui/#!iso:std:43001:en
ForTest methods for laser-induced damage threshold — Part 4: Inspection, detection and measurement:
https://www.iso.org/obp/ui/#!iso:std:43004:en

Because first we should know different terms and standard parameters related to it.
Hope this will help you.

[varinder singh]

hi zulkarnmain,

you are taking about the the nature of output of a laser with 1Gbps and the bias current of 10mA…. but you have not mentioned the type of laser component you are using….if u tell me the type of component ….then may be i will help you……..
with regards thankk you

[varinder singh]

Hi Zulqarnain,
We have different phase to analyse the complete lasers characteristics.
For est methods for the spectral characteristics of lasers , i would suggest you to visit this link:
https://www.iso.org/obp/ui/#!iso:std:43004:en

[varinder singh]

Hello Zulkarnain,
Though you are working on a low data rate and yet your eye diagram is not proper. Its strange. Could you please upload your .osd file because that way it would be more convenient to analyze what exactly you are doing. Can you detail about your other parameters that you are using for the transmission. Better would be to upload the .osd file so that people will help you accordingly. i Hope to se your problem get resolved soon.
Regards

[Ubaid Bhat]

hi zulkarnain…
i also agree with varinder singh in saying that eye diagram should be proper for low data rate but yours is not.so yo can try to vary other parameters like power etc to improve your eye diagram.you can also increase the gain of the amplifier for better results,but keep in mind that gain can be increased only upto an optimum level only as other non-linear effects come into play.
hope you got my point.
with regards.
ubaid bhat

[Ranjeet Kumar]

Hi ZULKARNAIN,
The eye diagram is not proper to analyze.
I think you should change the values of different global parameters.
You should check whether PBRS data rate is less than global data rate.
As many requested you to upload your osd file, so that we will help you.
Seeking your response.

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