Silicon germanium on graded buffer as a new platform for optical interconnects on silicon

We experimentally and theoretically investigate the use of silicon germanium (SiGe) on silicon substrate as a new platform for optical interconnects. The system composed of Germanium (Ge) rich Si1-xGex guiding layer on a graded SiGe layer is showed to be suitable for the realization of all main building blocks of passive optical circuitry. We show experimentally at a wavelength of 1550nm that sharp 12μm radius bends can be obtained by light confinement tuning. Mach-Zehnder interferometer with more than 10 dB extinction ratio is also demonstrated. Moreover, Ge-rich Si1-xGex based passive components are very interesting for their native integration with Ge-rich active optical devices. Hence, by using this new platform for optical integrated circuits, lattice mismatch between silicon and germanium is no longer a major constraint for the integration of Ge-rich active photonic components on silicon.