A short introduction to the theory of surface plasmon polaritons (SPPs) is given. The
application of the SPPs in on-chip signal processing is discussed. In particular two concepts
of plasmonic modulators are reported wherein the SPPs are modulated by 40 Gbit s electrical
signals. Phase and Mach-Zehnder modulators employing the Pockels effect in electro-optic
organic materials are discussed. A few micro-meter long SPP absorption modulator based on a
thin layer of indium-tin-oxide is reported.
