There seems to be some confusion here! Although OptiSystem is not the right simulation tool for this job, there is OptiFDTD that can simulate electromagnetic wave propagation in dielectrics and metals that could be of use to you Dina. We will need a little bit more information on waht exactly you are trying to simulate like some time of scattering simulation or absorption to get into more detail. Can you describe the device in more detail and which parameters you want to find?
Damian