Optical and electrical spectra of different MZM bias points

[Luis Vallejo]

Hello,

I am simulating a basic MZM at different bias points: Null, peak and quadrature. I follow the example that is shown in the Optisystem_Component_Library (pp. 736) without fiber.
I could see that the optical spectrum is ok, i.e. carrier suppression, strong carrier and multiple sidebands for null, peak and quadrature point.
However, the electrical spectra is not following the expected behavior. I mean that the generated electrical components are not right. For example, there should be some weak electrical carrier at 20 GHz, but I only can see the generated 40 GHz electrical component. It happens the same for peak and for quadrature point I can see the 20 GHz electrical carrier and 60 GHz electrical component, but I cannot see the 40 GHz electrical component (and it should be there).
Nevertheless, when I used fiber (for example 10 km), everything works fine!…: I can see the 20 GHz electrical carrier for null point, and 20, 40 and 60 GHz components for peak and quadrature point.

I think that something happens with fiber which makes the electrical spectra right. Some phase? I do not know…
Does anyone can help me? Because I need to show the MZM without fiber… but everybody will tell me that it is wrong.

Thank you

[aasif bashir dar]

See the phase of each optical spectra…. And check how the beating occurs at photodiode.. further have you used amplifier in link in case of fiber…. power of optical bands is not visible, there must be minimum threshold of power to generate electrical spectrum.

• This reply was modified 4 years, 3 months ago by aasif bashir dar.

[Luis Vallejo]

Thank you aasif. Could you tell me some brief instructions about how do I have to measure in Optisystem? or which component do I have to use?
I do not use any amplification, it is enough for now. The funniest thing is that I can see the bands when I use fiber (theoretically, it introduces losses..)
I also attach the scheme and the project.

[aasif bashir dar]

Very well Luis.. i have seen picture now.. it seems ok in power level… as far as phase of each optical spectrum is considered, such option is not available there.currently I do not have access to software however you can solve whole model theoretically.
As reference I am attaching a paper

https://doi.org/10.1364/AO.395712

[Luis Vallejo]

Thank you. Theoretically, I now that I have to see… The problem now is that the simulation does not show the correct results… and I do not know if I have used something wrong in optisystem
By the way, Thank you so much for the paper!

[Ahmad Atieh]

Dear Luis,
I’ve check your projects. The issue is related that the pin detected is a square law device and caused some components to disappear in the ESA. The long length fiber introduces some phase information for the missing components which allows them to appear on the ESA. Please note that when I’ve decreased the length of the fiber to 100m, the 60GHz signal disappeared as shown in the attached file.
There is a component in OptiSystem called “Optical Phase Detector” which shows all components generated by the MZM.
Regards,
Ahmad

[Luis Vallejo]

Thank you Ahmad. I will take into account and I will check the phase.

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