Silica-based optical interposer for Si photonics

An important advantage of Si photonics devices is their compactness, which derives from the high refractive index of Si. However, this compactness also causes a problem for a specific application. To solve this problem, the paper proposed an optical interposer for Si photonics. In this concept, the fan-out waveguides , which are pitch-changer waveguides, were positioned outside the Si photonics device on a silica-based waveguide. And the silica-based waveguide and Si photonics device are optically coupled via a mirror array on silica and a Si grating array, which allow vertical coupling to Si photonics devices with a wide alignment tolerance. This interposer can keep the Si photonics device small and allows us to layout a large number of chips on one wafer. In this work, we realistically expect the loss of the interposer and show its potential.