Spatial Visualizer

[Ahmad Mustafa]

Hi,

I use one Spatial CW Laser source and split it into two and a Rotation Angle of 90 degree is introduced in one of the arms so to have the signal in this arm polarized in Y direction.

I can rightly see so on the Spectrum Analyzer and View Signal Visualizer as one signal is X polarized and the other one is Y polarized. But both the signals/fundamental modes appear on the X Polarization in the Spatial Visualizer and there is no signal when I choose Y Polarization in Spatial Visualizer.

Can someone explain the issue here?

Please find the attached .osd file to see it.

Thanks!

[Damian Marek]

Hi Ahmad,

Thanks for pointing this out. The Polarization Rotator is not correctly calculating the new spatial distribution. If you want to rotate your spatial signal I would suggest using the Spatial Connector as well. It will rotate the spatial signal by as many degrees as you. However, it will not automatically rename the mode as a Y polarized mode.

[Ahmad Mustafa]

I have introduced the Spatial Connector block after Polarization Rotator having Rotation Angle= 90 deg. The Spatial Connector has 90 deg Y tilt (to polarize the signal in Y direction) and after the MUX, I can see the two signals on the OSA polarized in X and Y. After the Parabolic-Index MMF, the signal power is dropped down to zero although the length and attenuation values of the MMF is negligible.
If, however, I take out the Spatial Connector block then everything works fine.

I do not understand the role of Spatial Connector here as I would expect it to just rotate the polarization by 90 deg and it should not have effect on the signal power after the MMF.

Can you please elaborate if I am using this block correctly or if there is some other conceptual issue here?

Attached is my simulation file for your consideration.

Thanks!

[Damian Marek]

Hi Ahmad,

The problem here is that Y tilt and Rotation are not describing the same physical position of the two facets. The Y tilt and X tilt change the angle of the transverse plane, which is normal to the direction of propagation. The Rotation parameter actually rotates the transverse plane around the Z axis (propagation direction), this is the parameter you should be changing. I’ve included an example, which is a slightly edited version of yours.

Look at mode 1 at both Spatial Visualizers, the second signal is rotated by 90 degrees. I hope this explains it! If you are having trouble visualizing the 3D model these parameters are describing, let me know and I can make a simple diagram.

Regards

[Ahmad Mustafa]

here is the simulation file.

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