Dear Devika,

My very first attempt is using FDE, but I realized that FDE only takes into accounts of the material's imaginary refractive index (I ran two different simulations, one with actual material parameters with , one with object-defined material parameters without imagnary refractive index). It turns out that the one without imagnary refractive index gave no propagation loss. This is why I used VarFDTD (as the authors mentioned). I will check out more carefully the link you sent me. 

Thank you