I am trying to reproduce the paper: Complete optical isolation through indirect interband photonic transitions
The non-reciprocal transmission they have demonstrated in fdtd by their in house simulation code. I want to reproduce the same results by spatiotemporal varying the relative permittivity in comsol multiphysics.
I have simulated using the physics ewt(electromagnetics transient) and the study is time dependent. Seperately I am defining epsr(x,t) as analytic variable then using it in wave equation for the silicon choosing epsilonr (relative permittivity) as user defined. I have used for isotrpic case & diagonal case. There is no change in the FFT at the probe position with plane wave excitation. Frequency sweep has also been applied. There should have some change at the FFT probes (upshift or down shift in frequency). Is this the correct way of modelling this dynamic permittivity modulation or there are some other ways to do it, if any.