# Negative index of refraction transmission

Hi guys,
I have slab of negative index of refraction material, inside the material the evanescence field is amplified. I want to calculate transmission of this slab for evanescence waves, so I used fresnel equations with multiply reflection inside of slab. I found this method in some papers. First question is, how is possible that I can use geometric series of reflection inside the material, I have evanescence field, which doesnt propagate, so what is it reflected? If I use Fresnel equation for transmitted field I get for epsilon=-(1+delta) and mu=epsilon. How is possible that I get more than one, is that means that it is like superpossition of bounded surface mode and evanescence field which is transmitted? if I use epsilon=-(1+i*delta) and mu=epsilon, the peak disappear, so basicaly I introduce small absorption with imaginary epsilon what is the principle which cause this abrupt change(I think that I have evanescence wave, so it means that my wave vector in z-direction is choosen to be real, so if I introduce imaginary epsilon I will get imaginary part of kz which means that I have propagation wave not absorption.)

It is not clear to my how is possible that if I have slab of metal with negative only epsilon, and I want to excite the plasmon wave the energy will transfer from one interface to another(Kretchman configuration). Evanescence wave doesnt carry energy, so how can this happen?

Please, if you can suggest some advice or some reading to understand these things I will appreciate it so much