what is the inner structure of the Optical Ring Modulator ?

I choose this item in modulator:

There are two waveguides around the rings with 4 ports, but actually only 2 ports operable. So I wonder which port is linked to the green one.

Hi @james_zhan,

Either the upper waveguide or the lower waveguide is connected to the green line. Basically the optical signal inputs to one of the four ports (of the double bus ring modulator) and then the output is measured at the trough port.

I hope this could help :slight_smile: Let me know if you have further problems.


When I apply DC voltage to the modulator, the spectrum does not change at all, what is wrong with it?

Hi @james_zhan,

There are several possibilities that can cause this problem, but basically almost all related to the setting of the ring modulator. Could you please attach your file here (or screenshot everything) so that I can pin point the problem? :slight_smile:

Hi @james_zhan,
If you are using the default measurement of the ring modulator, then you won’t see the desired spectrum shift due to the very week electro-optical properties. I attached a file here with another measurement set. You can observe the spectrum shift with changing the DC voltage between 0 and 0.15.
You can load your own data file that represents the desired electro-optical effect.
I would also recommend that you check this KB page:

Optical_Ring_Modulator_Aya.icp (130.3 KB)

Hope this helps!


It does help. Thanks a lot !

I have found the problem. Thx all the same.

Is this measurement from experiment or just set casually? I have been successful in simulation but still needs to check the data source.

Hi @james_zhan,

I am not totally sure about the answer, but by looking at the data, I think it is a reasonable guess that the it comes from some experimental results. You can definitely populate in some casual data for the ring modulator for toy models just to test out the design; while for realistic designs, you can use MODE Solutions + DEVICE to get the effective index changing versus voltage changing coefficients. The detailed simulation procedure is discussed in the Travelling Wave Modulator (TWM) page. The example is for a Mach-Zehnder based modulator, but the same process can be used for ring modulators.

I hope this could help :slight_smile:

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Ok, thx。。。