Learning Forum

[a.lechiara]

Hello everyone.

I have been trying to simulate Kerr nonlinearity in a ring Resonator in Lumerical MODE without success and I would appreciate some support in this regard. From my calculations I expect a value of Chi3 = 1e-18 [m^2/V^2].

I am using Chi3 Raman Kerr on top of InP - Palik and Chi3 = 1e-18 [m^2/V^2] value.

The simulation time of VarFDTD is 50000fs and I am injecting one Pump mode and one Signal mode corresponding to two of the allowed frequencies in the Ring resonator.

The issue is that I am not able to observe any interaction given that value of Chi3. As soon as the Chi3 increases to an unphysical value such as Chi3 = 1e-6 I can see the expected nonlinear interaction.

 

Is there a coefficient to be kept into account when choosing the chi3 parameter in the material database?

What could be the issue?

 

Thanks in advance for your support

[Dev]

Hello

My suggestions are the following:

When dealing with the Chi3 parameter, it's important to ensure that the value used in the simulation closely represents the physical system you are trying to model. Please refer the following: Ring resonator - optical bistability – Ansys Optics

If you are not observing any interaction with a Chi3 value of 1e-18 [m^2/V^2], it could be due to several reasons. From what I know, the field intensity in your simulation might not be high enough to observe the nonlinear effects with such a small Chi3 value. It's also important to ensure that the simulation setup, including the source customization and the time monitors, is correctly configured to capture the nonlinear interactions. Please see the following: Four wave mixing (varFDTD) – Ansys Optics

It's also worth checking if there are any additional coefficients or scaling factors applied within the simulation environment 

1. Check the dispersion profile of your ring resonator (group index vs. wavelength): If your signal and pump modes are not phase-matched, the nonlinear interaction may be suppressed.
2. 50000 fs (50 ps) might not be enough for significant nonlinear interactions if the field builds up slowly.Try increasing simulation time to observe accumulative effects.
3. Try increasing the input power (pump intensity) while ensuring that it's still within the physically meaningful range since the Kerr effect is highly dependent on the electric field intensity I=∣E∣2I = |E|^2I=∣E∣2.

Hope this helps.

Thanks