In this book, novel plasmonic devices are designed and demonstrated. In particular, an ultra-compact phase modulator is reported by exploiting plasmonics and Pockels effect in electro-optic organic materials. An absorption modulator with a length of few micrometers is designed and demonstrated. To efficiently interface plasmonics with low loss silicon photonics, novel photonic-to-plasmonic mode converters were developed. Finally, a new ultra-compact polarization beam splitter (PBS) is presented.