Optical absorption in MIM or MSM plasmonic structure

Hello,

I am studying the plasmonic effects on Metal-Si(SiO2)-Metal structure . I try to calculate the total optical absorption (1/m) on the surface of the structure using the Total Power Dissipation Density (emw.Qh). Did I use the correct option to get the logical result or should I use the other one?
However, emw.Qh gives both positive and negative value which I cannot understand. I thought that the total power dissipation density should be positive. Can you please comment on this and tell me where I am going wrong?

Best,
Hamed