WDM-MUX

[FAYIQA NAQSHBANDI]

Hello every one.

I am using a WDM multiplexer to stack four wavelength channels in a TWDM-PON.I am achieving a good system performance for downstream for each of the four channels.Also i have assumed the insersion loss due to the multiplexer is zero.
But when in the same system,i replace this MUX with an ideal MUX,my system shows a drastic improvement in the performance.
What is it that an ideal MUX ignores apart from the insertion loss which i had already assumed zero in the first case ? and
Why do i see a huge diffrence in the performance of the two ?

[aasif bashir dar]

hi fayiqa,
itz not only insertion loss that cause change in performance.in practical MUX the input power of different wavelength do have interaction.yOU might have heard of AWG MUX, in which input wavlength combines and produce constructive and destructive interference.

thus practical is always lossy apart from insertion loss

with regards

[Aabid Baba]

Hello fayiqa,
I have come across same thing in my system design too. Well , if you might have noted that power levels come down drastically after MUX ( if you ever checked power levels of signals right after Mux) but that is not the case with Ideal Mux. Infact, there is no drop after ideal Mux. I presume that ideal Mux has every attenuation factor , dispersion factor and other such factors set to zero (by default). That is why the performance is better in case of ideal Mux.
But i would also love to know the real reason behind it.

[Naazira Badar]

Hi all..
here’s the link to a related post: https://optiwave.com/forums/topic/optimize-system-performance-when-using-dwdm-mux-not-ideal/

I think this seems convincing enough that ideal MUX puts no limitation of the bandwidth constraint as mentioned rightly by Alistu. Hence the results are better, since no interference takes place. However,in practical systems the bandwidth and other losses are an important consideration. So, I would suggest using a non-ideal WDM MUX for making the simulation results close to the practical scenario.

Regards.

[alistu]

Allow me to bring an example from another component that does not exist in practice and yet is widely used in OptiSystem: Fork. Aside from this, in many cases where the signal falls into the pass band of the filter, we can make the simulation just by using an ideal MUX and only adding insertion loss. In such cases, the result won’t be far from reality.

Regards

[aasif bashir dar]

hi all,
ideal mus or demux in optisystem are like black box with function to seperates or combines the individual wavelengths. there not practical importance of these components ,but for simple simulation purposes we can use them.
besides they are ours models so as configure our practical MUX deMUX for practical purposes

with regards

[FAYIQA NAQSHBANDI]

Naazira..Thank you for posting the link.Yes The difference between the transmitter bandwidth and the MUX band width can be a valid reason for the difference in performance.So i think we can achieve a good performance with the practical MUX if the bandwidth constraint is taken care of properly.

Regarding the power level.Yes i agree that an ideal MUX shows exacly the same power at its output as is fed at its inputs.
But considering all this now my question is

Why does optiwave even have a component like ideal MUX if we can’t use it to design our systems..There is no other ideal component like an ideal fiber..an ideal transmitter or an ideal receiver. ?

[alistu]

Hi Fayiqa,

Ideal MUX can sure be used in system designs for theoretical purposes. Besides, since the ideal MUX acts like an ideal adder (of course it wouldn’t be that ideal if you set a value for insertion loss), sometimes it can be used to make subsystems and components. This doesn’t necessarily mean all OptiSystem users would need to use this component, though.

Regards

[Naazira Badar]

Hi all..

I think, since WDM systems are used widely, it must be as an aid for testing the system at some levels. eg. a connection, So that we could check if our components of our WDM system are working. But you should still get it confirmed about the system support about this.

Regards.

[FAYIQA NAQSHBANDI]

Thank you all for your responses 🙂

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