Optical design of active interposer for high-speed chip level optical interconnects

Based on the precise evaluation of optical coupling tolerances between vertical cavity surface emitting lasers (VCSELs) and an optical waveguide film with a 45° mirror, optical interconnection modules entitled "active interposers" have been designed. To evaluate the optical coupling tolerances caused by misalignments, we introduced a novel analysis using contour plot. Using the contour plot, a clearance of 60 μm between the VCSEL and the optical waveguide film was employed to produce sufficient optical coupling. The active interposers comprising driver and receiver ICs, the VCSEL, the photodiode (PD), and the interposer were assembled by a passive alignment on a printed circuit board (PCB) having an optical waveguide film. Using fabricated active interposers, multi-Gb/s transmissions were successfully obtained. The active interposers, fabricated on the basis of optical design, have been found useful for high-speed chip level interconnects.