Modulation schemes for studying the output optical power of laser

[ZULKARNAIN]

Hi all….
i am currently studying the optical output power from a laser depending on various parameters of the Laser and the input signal.In my previous post i mentioned the effect of increasing input power of the laser and the use of RZ,NRZ sequences.
Now i would like to know about the various modulation schemes that can be used for observing the output from a laser.

[Tanveer]

hello zulkarnain,,,
the various types of modulation schemes are external modulation (which include two techniques electro absorbtion modulation and electro opto modulator)..
another technique isDirect Current Modulation of ssemiconductor laser.

moreover you can refer the links

http://www.ijcem.org/papers72011/72011_17.pdf

http://www-ee.stanford.edu/~jmk/pubs/mod.and.det.tech.COTA.6-06.pdf

regards

[ZULKARNAIN]

Thank you Tanveer for your reply…
can you tell me which one will be better for my project and why will be it better??
Answer will be appreciated..

[Aabid Baba]

Hi zulkarnain,
I would suggest you to go through all the digital modulation schemes and then apply a modulation scheme as per your requirement. if your requirement is met by some of the modulation scheme then you would be done. You can compare results for different modulation schemes and then check which one gives the best results as per your requirement. Hope it is helpful.
Regards

[Aabid Baba]

Hi zulkarnain,
As far as modulation schemes are concerned, there are number of digital modulation schemes you can use for your system design. Please it would be convenient if you try to be more specific regarding your system design. However, i am attaching a link which mentions different digital modulation schemes. You may refer to it for further reference. It would definitely help you.
https://optiwave.com/category/products/system-and-amplifier-design/optisystem/optisystem-applications/advanced-modulation/
regards

[Tanveer]

hello zulkarnain..
can you please share the basic info of your project, the goals which you want to achieve from the project ,,,
regards

[ZULKARNAIN]

thank you aabid baba for your reply…
I am studying the optical output power from a laser depending on various parameters of the Laser and the input signal like different modulation schemes and the various input parameters like varying input bias current, the input bit rate.
Can you tell me about the modulation schemes which will be better to work on?
Answer will be appreciated..

[Aabid Baba]

Hello zulkarnain,
To my understanding i guess you are referring to different modulation schemes. Well there are many which could serve your purpose but as i mentioned in last comment you must implement few of them to your system design and check for the performance. I would suggest to use QPSK or DP-QPSK or for that matter QAM. You can check which gives you the better response and then proceed accordingly.
regards

[ZULKARNAIN]

Tanveer you can refer to the reply which i addressed to aabid baba for the basic information of my project.

[Tanveer]

hi zulkarnain,,,,,,
you may please refer through the links provided………there is a good comparison between the modulation techniques provided….

http://www.cpeu.dk/data/uploads/teaching/34129_e2009_cpeu_dml_eml.pdf

http://www.dli.gov.in/data_copy/upload/INSA/INSA_2/20005ad1_228.pdf

hope it helps you to get the clear idea for your project requirements…

with regards

[ZULKARNAIN]

thankyou tanveer for your reply…
indeed the links you forwarded were good to refer and they have given a good comparison between the modulation techniques.

[Aabid Baba]

hi zulkarnain,
I hope you got a good idea about different modulation techniques and their implications in different designs. I would suggest you to implement all the modulation techniques mentioned in my previous comment and compare results based on these modulation scheme. I hope it will help that way.
best regards

[Ranjeet Kumar]

Hi ZULKARNAIN,
You can also vary laser power for advanced modulation schemes like CSRZ, MDRZ, DRZ and plot the simulated results like Q-factor and Min. BER against Optical power.
So, i am uploading 8 channel CSRZ modulation schemes of WDM system.

Attachments:

1. 8channelCSRZ3.osd

[Ranjeet Kumar]

Hi ZULKARNAIN,
So, i am uploading 8 channel DRZ modulation schemes of WDM system. You can plot its results vs optical power of laser

Attachments:

1. 8channelDRZ1.osd

[Ranjeet Kumar]

Hi ZULKARNAIN,
So, i am uploading 8 channel MDRZ modulation schemes of WDM system. You can plot its results vs optical power of laser

Attachments:

1. 8channelMDRZ1.osd

[ZULKARNAIN]

Thank you ranjeet for uploading the osd files of advanced modulation schemes.
But i am studying the effect of some basic modulation techniques and then i will go for advanced schemes.

[Tanveer]

hi zulkarnain…
you just stick to basic modulation schemes and study their effects for various parameters and then compare the results obtained with your requirements,,,,.. hope you will get the idea what to select for your project,,\

with regards

[ZULKARNAIN]

Thank you tanveer for your reply.
You are right that i should go for basic modulation techniques. To some extent i got the idea that how i should compare the results.
Also i would like to thank you everyone for their answers and valuable time.

[aasif bashir dar]

hi zulkarnain,
as far as simulation purposes are concerned you can use different modulation formats like RZ , NRZ….

but the output power will always remain equal or less than that of the laser power(cw laser) after the modulation,

how ever the power spectrum will be in accor to that of modulation format or scheme.

hope you got my point.

with regards

[ZULKARNAIN]

thank you aasif for your kind reply.
i got your point and actually i am studying the optical output spectrum of the laser. i had wrongly wrote optical output power instead of optical output spectrum.
Will you please tell me which modulation scheme Return To Zero or Non Return To Zero will give better output spectrum.
Answers will be appreciated.

[Tanveer]

you are welcome zulkarnain…

[Tanveer]

you are welcome zulkarnain…

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