Several planar layouts of plasmonic waveguide modulators that utilize alternative CMOS-compatible materials are proposed. The modulation is efficiently achieved by tuning the carrier concentration in a transparent conducting oxide layer. Alternative designs that utilize field amplification by semiconductor gain materials or ferroelectric domain switch and consequent refractive index change will be presented as well. Collective lattice resonances in plasmonic nanoparticle arrays to enhance photoelectron emission in Schottky-barrier photodetectors and solar cells will be discussed. Finally, if time will allow, the mechanisms responsible for enhanced transmission of electromagnetic wave through an array of subwavelength slits in metallic films will be presented.