OTDM

[Arpita Gupta]

I am simulating the 4 user transmitter and receiver network but i am not getting the proper eye pattern at 2Gbits/s so i need the help. i am not getting the problem. I am attaching the layout.

[alistu]

Hi Arpita,

I managed to increase the eye opening a bit by using ideal MUX instead of power combiner. In your OptiSystem version, the power combiner output power is the average of the input power, but in the ideal MUX the input powers are all added. In version 14, though, the function of power combiners has been modified.

Regards

[Arpita Gupta]

I have applied the IDEAL Mux but i did not get the any improvement please see the layout and solve my problem

[alistu]

I managed to make a rather small improvement in terms of Q-factor (which corresponds to eye opening), increasing from about 3.3 to 4.1. Other than this, I decreased laser linewidth to 200kHz (which is commercially available) and also increased laser power, but none made any significant difference.

[aasif bashir dar]

hi arpita

can please post ur screen shot of .osd file, i dont have acess to optisystem this time.

with regards

[Arpita Gupta]

i am attaching the image of design and i am not getting the output proper as explained in the optiwave software design example.

[alistu]

Hi Arpita,

I only suggested using “ideal MUX” instead of power combiner, but I see power splitter has also been replaced. Even though this does not make any serious problem, I suggest you replace it with power splitter if you like, since power splitter does not have the problem that is there in combiner in OS13.

Regards

[aasif bashir dar]

hi arpita

i have gone through your .osd degn pic.what i saw in your attached pic is that you are using the mux and demux……

1.but we use mux and demux while we are transmitting at several wavelengths.and you are using only one wavelength.hence in my view your .osd design is logically wrong. you are using time divison for single wavelenth which is optical timing division multiplexing(OTDM).

2. i think you are trying to form hybrid network i.e time divison wavelength multiplexing.

with regards

[alistu]

Hi Aasif,

The ideal MUX that I suggested to be used acts the same as a power combiner, so the use of it causes no problem and on the contrary, makes the design perform better since the output power is not the average of the input signals (unlike power combiner component in OS13), but it is the sum of them. So it would be OK to use it in such configuration.

Regards

[aasif bashir dar]

you go through these .
1.https://optiwave.com/resources/applications-resources/optical-system-time-division-multiplexing-tdm/

2.https://optiwave.com/resources/applications-resources/optical-system-optical-time-domain-multiplexing-otdm-design/

if you replace ideal mux by power combiner and demux by power splitter , you will get very good results.
do this and and let me know about about your results..

with regards

[alistu]

Other than what I suggested about use of MUX, I believe the system Arpita has implemented is not a hybrid system. The splitter used after the laser is just to distribute input optical power. If not, could you explain how the system is hybrid. I hope Arpita does not get confused by the suggestions.

[aasif bashir dar]

hi alistu
please how had you suggested the use of mux with single wavelength. this is bizarre.

with regards

[alistu]

I have made the explanation in my first comment in this topic page. Aside from that, please refer to the following forum page where I have raised a question regarding their performance, whose answer would hopefully clear your doubts:

Power Reduction in Optical Combiner

Regards

[aasif bashir dar]

mux is for several wavelengths. this is getting worse .

please explain the use of mux and demux for single wavelength, instead of power combiner and splitter

[alistu]

I only suggested using MUX, ant not DEMUX. But even using DEMUX does not worsen the performance of the system! it acts like a fork and copies the input signal to all the output ports, so that is why I suggested Arpita to replace the MUX to have a more practical implementation. So no degeneration should occur.

[Arpita Gupta]

i have also performed the design with combiner but i did not get the result

[alistu]

Please use an Ideal MUX at transmitter and use a power splitter at the receiver as you were formerly using. The modifications within your system should be made in other components. If you have any questions about the ideal MUX, please feel free to ask (to understand exactly why I suggested it).

[aasif bashir dar]

hi arpita
have you replaced demux by power splitter.

[Arpita Gupta]

Yes but this did not helpful.

[Aabid Baba]

Hello arpita Hi asif,
people i agree with asif. You can’t use Mux as a power combiner here. Logic is fine you can split power of input signal and combine it. But i would suggest power combiner rather than mux. mux is primarily used for time division multiplexing. You would get only one signal at each time slot. If you wish to recombine the power you must use power combiner.
As i can see from the screenshot she is trying to split input power and MULTIPLEX it rather than combining it.
regards

[alistu]

Hi Aabid,

As you can see from the answer given by Philip Weetman, the Optiwave engineer, the new power combiner acts EXACTLY like the ideal MUX component. However, in older OptiSystem versions the power combiner was based on a model that Philip stated was not correct. This is his answer:

Power Reduction in Optical Combiner

[Aabid Baba]

Arpita could you attach your osd file. ??
we can try something respectively.

[alistu]

Hi Aabid,

The .osd file is already available on this forum page. You can find it attached to Arpita’s main post. You only need to replace the power combiner by an ideal MUX, as I have been explaining (since Arpita is using version 13 and so on).

Regards

[aasif bashir dar]

hi alistu,
please visit the link for discussion,

Power Reduction in Optical Combiner

with regards

[Arpita Gupta]

i have been performed the analysis with ideal mux and optical combiner and splitter but no change observed in BER. please see the .osd file

[aasif bashir dar]

hi arpita ,

i suggest you also to visit the above the link to clear your confusion above the power combiners and ideal mux

with regards

[aasif bashir dar]

hi arpita,

i suggest u to visit the above to clear the confusion about power combiner and ideal mux.

with regards

[Aabid Baba]

Hi arpita.
I guess you shouldn’t be using delay at the first input. You can receive it with zero delay but you must keep the delay for other corresponding inputs.
I tried to simulate your osd file.

[Arpita Gupta]

I have also apply the analysis with the IDEAL MUX and combiner and splitter but i did not seen any improvement so i confuse where is the problem.
I am attaching the .osd file please see this

[Aabid Baba]

your sent osd file is not running. I am getting an error while simulating it. Are you able to simulate it..?? It shows an error message ” component calculation not complete”. Please look in the design again and send an osd file which is running atleast.
regards

[Aabid Baba]

This is exactly what it shows when i try to simulate it. are you working on optiwave 7 /13 or 14 ??
may be compatibility issues i guess. Anyway please see to it.

[Arpita Gupta]

I am simulated with the optiwave 7 please see the latest attachment

[Aabid Baba]

It again shows the same message. Are you able to simulate it and note the eye diagrams and all?
i am not able to simulate it leave apart checking for results. I guess there is some compatibility issues. I find it very strange that its not working on optiwave 14 when it should easily work. I will see to it.
appreciate your patience

[Ranjeet Kumar]

Hi Arpita,

Use WDM demux in place of power splitter to remove error.
hare, i am aataching edited file.

[umer ashraf wani]

Apita mam use fork instead of power splitter

[Ranjeet Kumar]

Hi arpita,
I here uploading an osd file OTDM.

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