Hi,

I am attempting to simulate in comsol a nonlinear metamaterial (which by using effective media theory I can approximate as a periodic slab of artificial material).

My process is as follows:

Run a frequency domain study, this contains my model, a propagating wave (from the emw port). I perform the comsol study and place domain point probes at points of interest. I monitor the Ex, Ey, Ez, and normE here.

Next, I find the voltage at a point in my material (at split of my split ring resonator) simply by multiplying a component of the E field at this point by the gap size of the split in the ring.

Next, I couple a time domain study of my model to a circuit model so I can apply a voltage source. I am looking for the second harmonic so I apply V(2w) =1/2 a(Vw)^2 voltage (from an expansion of the voltage in the linear model with 'a' being a nonlinear co-efficient which I will know).

Following this, I have a scattered boundary condition as a source of the field I have saved from my emw.Ey etc run from the frequency domain and I use a polarisation term to couple the incident field chi(2) *(emw.Ey)^2, where chi has been found via an equivalent circuit analysis.

I then export my time domain results to matlab (just for sake of ease as I'm more familiar with matlab) and take the abs(fft(Efield)) to find the frequency content of the output from my model.

I'm aware this method is probably incorrect, but any pointers, or corrections from correct comsol usage to correct method to simulate nonlinear materials, would be greatly appreciated.

Thank you very much