A research synopsis is presented summarizing work with integration of Ge and III-V semiconductors and optical devices with Si. III-V GaAs/AlGaAs quantum well lasers and GaAs/AlGaAs optical circuit structures have been fabricated on Si using Ge/GeSi/Si virtual substrates. The lasers fabricated on bulk GaAs showed similar output characteristics as those on Si. The GaAs/AlGaAs lasers fabricated on Si emitted at 858nm and had room temperature cw lifetimes of ~4hours. Straight optical links integrating an LED emitter, waveguide and detector exhibited losses of approximately 144dB/cm. A process for fabrication of a novel CMOS-compatible platform that integrates III-V or Ge layers with Si is demonstrated. Thin Ge layers have been transferred from Ge/GeSi/Si virtual substrates to bulk Si utilizing wafer bonding and an epitaxial Si CMP layer to facilitate virtual substrate planarization. A unique CMP-less method for removal of Ge exfoliation damage induced by the SmartCut™ process is also presented. / Singapore-MIT Alliance (SMA)