simulation time

[Aabid Baba]

for a same system set-up if i use an optical amplifier with an output power of 10dBm,simulation completes in harldly 2-5 minutes.
but when an optical amplifier with a gain of 5dB is used the same system takes around an hour to simulate.
why is there a huge difference between the use of two amplifiers ?..which one should be preferred & when ?
Any help??

[alistu]

Hi Aabid,

10 dBm equals -20dB. So when you are using 5dB amplifier, you have actually increased the power about 25 dB, and when rather large power is injected into the optical fiber, the nonlinearities kick in. This is when the calculations take longer and the system performance deteriorates.

Regards

[aasif bashir dar]

hi aabid baba,

i agree with alistu, large power take longer time on optisystem. I appreciate his explaination.

with regards

[Aabid Baba]

Thank you alistu.
Any suggestions to minimize the simulation time? or is there any other way to use any of the amplifiers with such parameters?
i need a power output and gain output.. can there be a way to somehow convert power output to equivalent gain output.

regards

[alistu]

You’re welcome. Unfortunately, nonlinearities are a serious constraint on today’s systems and the only way to avoid them is to reduce gain of the amplifiers or the power that enters the optical line. Can you please elaborate on what you mean by “power output” and “gain output” in the above statement?

[Aabid Baba]

Yeah it actually is a serious concern but that’s how it is going to be. Every software comes with some sort of shortcomings. In optiwave itself, I have seen many components not working properly or performing functions they are supposed to perform. We ought to add parameters that are not required at first place just for sake of simulation. Anyways, i was referring in context of output power and gain of amplifiers as i had mentioned in #30241.
Appreciate your response.

[alistu]

Well, gain causes the power to rise. So either way, we can talk about the power entering the optical line. There is one thing that sometimes can be done, though. Sometimes instead of adding amplifier power, it is possible to increase laser power so as to avoid the noise figure produced by lasers and get better signal while keeping power level the same.

[aasif bashir dar]

hi aabid and alistu,

power increse in the fiber causes the reffective index of to change.AS the power level in the fiber is not constant through out fiber. it various along the length of fiber and also with the times. hence a changes behaviour of core reflective due to high power density leads to what we called the Kerr’s non-linearity.

with regards

[aasif bashir dar]

besides non-linear effects do not have the dark side. these effects are also helpful and are vary much extensively studied.
the below links provide the introductory concept of nonlinear effects , advantes disavantages and application.

1.https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjkrMa14JXLAhWGCI4KHY01Bx8QFggiMAA&url=http%3A%2F%2Fjpier.org%2FPIER%2Fpier73%2F13.07040201.Singh.S.pdf&usg=AFQjCNF1l4JThMdRAAkt3e1rYPVE2tAO_w&sig2=lACcGuW4ZNRIIfi3g9BjSw&bvm=bv.115339255,d.c2E

2.https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwjkrMa14JXLAhWGCI4KHY01Bx8QFgg1MAM&url=%2Finterstitial%3Furl%3Dhttp%3A%2F%2Frimtengg.com%2Fcoit2008%2Fproceedings%2FNW37.pdf&usg=AFQjCNHzjWRhvXfyr9_P7dO4SiI5wgeBtQ&sig2=IohxSZ0TvW-9mSFyZcZdzw&bvm=bv.115339255,d.c2E

3.https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwjkrMa14JXLAhWGCI4KHY01Bx8QFgg8MAQ&url=http%3A%2F%2Fwww.ece.virginia.edu%2F~optcom%2FDissertations%2FDissertation_Bo_Xu.pdf&usg=AFQjCNFKtUFTMRArJBUr-e766m4edHHLBQ&sig2=N1-ePhxtkhezkhX7chl8eQ&bvm=bv.115339255,d.c2E

with reagrds

[Aabid Baba]

no doubt power levels increase with gain but as per ITU-T standards i can’t increase laser power beyond a certain level that is why i used amplifiers with power output and amplifiers with gain to better performance of my system.
Please alistu can you further explain the last two lines of the comment #30329. I am not getting what do you mean by ” increasing laser power keeping power level the saame” . which power level you are talking about??

[alistu]

Certainly if some standards are followed, the power cannot exceed some certain value. That is exactly why I have used the word “sometimes” in my statement if you will.

By “the same level of power” I mean the same level of power injected into the line. This power is the sum of power from the laser and the gain of the amplifiers.

Regards

[Aabid Baba]

Asif thank you for your wise words.

okay Alistu thank you so much. Could you please suggest if there is any way to completely avoid amplifiers with power output and amplifiers with gain and still get a best possible performance. Actually , that can help me in cost budget analysis too. I would appreciate any further help in this matter.

regards

[alistu]

You’re welcome Aabid. Whenever you reach the system input power limit (the power entering the line reaches a point where power degrades performance), nothing can be done in terms of power. If you are seeking other ways, please insert your system implementation and I will look into it.

Regards

[Aabid Baba]

Thanks alistu for your kind gesture.
Its alright. If you somehow find any relevant topic or material , please post it on this post only. I will be looking forward to that.

It was so nice and helpful discussing and sharing things with you.
Thank you again.

regards.

[alistu]

You’re welcome Aabid. I will definitely let you know of any additional points in this regard in terms of systematic effects of input power (though physical explanation of the process seems irrelevant to your topic, so I’ll avoid that). For the rest of the system check, the file is required though.

Regards

[Aabid Baba]

Thank you alistu,
i would try to simulate a separate module in which i would in-cooperate both amplifier with output power and amplifier with gain and upload it hopefully.
That way you would get an idea what am talking about and what is my exact point so that you could manipulate things for that system and get a better results.

Regards

[alistu]

In most of the systems, both optical amplifiers and laser sources are used (OptiSystem example implementations can be referred to for instance). So this is not as unusual as one might imagine. Anyway, I will be here to provide help if possible after you attach your system design.

Regards

[Aabid Baba]

hopefully soon.
Thank you Alistu for your efforts. I appreciate

[alistu]

You’re welcome Aabid.

Regards

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