Hybrid interconnects using silicon/FR-4 substrates for board-level 10 Gb/s signal broadcasting

An opto/digital interconnect prototype for board-level 1times4 optical-to-digital signal broadcasting operating at 10 Gb/s per channel over an interconnect distance of 10 cm is demonstrated. An improved 1 times4 multimode interference (MMI) splitter at 1550 nm with linearly-tapered output facet is heterogeneously integrated with 4 p-i-n photodetectors (PDs) on a silicon (Si) bench. The Si bench itself is hybrid integrated onto an FR-4 printed-circuit board (PCB) with 4 receiver channels. A novel fabrication/integration approach demonstrates the capability of simultaneously aligning multiple polymer waveguides with multiple optoelectronic (OE) devices during the waveguide fabrication process. The combined excess loss of the MMI splitter and the mirror loss per channel is less than 3.5 dB and the entire system is fully functional at 10 Gb/s