electrodes design for EO polymer waveguide

hi, there are some problems i hope i can hear ur suggestions.

in order to get a parallel E-field which will induce the index change of EO polymer, where should the electrodes be?

whether on the channel in vertical direction or on two sides of waveguide in horizontal direction?
which one give better results? and does EO require the E-field should be very parallel or doesn't really matter?

if so, how can the thickness of the electrodes be achieved since mostly the sputtering can only achieve several nm.

thank you so much