This book presents design and analysis guideline for compact and high speed optical modulators using electro-optic polymer-assisted hybrid plasmonic /silicon photonic technologies. Two types of modulators are addressed here for optical communication systems, binary ring modulator and 16-QAM Mach-Zehnder modulator (MZM). The theoretical predictions are supported by simulation results obtained using COMSOL and Optisystem software packages. The first part presents analysis and investigation of 1550 nm and 1310 nm ring optical modulators employing an electro-optic polymer infiltrated silicon-plasmonic hybrid phase shifter. The second part presents the design and investigation of 1550 nm 16-QAM optical modulator based on plasmonic-polymer hybrid slot waveguides. The design is CMOS-compatible and uses dual-parallel Mach- Zehnder modulator followed by a phase modulator.