Surface Integration with different modes

Hi all,

I have calculated the results for the different transverse modes in an optical waveguide using the Mode Analysis solver in the RF module. Now I want to perform a surface integration across one domain, say I want to integrate the electric field in x-direction (emw.Ex) inside the core. I can do that for one of the found modes.

Is there a way to get the surface integration for the multiplication of the electric field for two different modes, i.e.

emw.Ex(of mode1)*emw.Ex(of mode2) ?

Thanks a lot
Patrick