1-GHz clock signal distribution for multi-processor super computers

In this paper, we present our efforts to construct an optoelectronic interconnection layer for high-speed optical clock signal distribution in a Gray T-90 supercomputer board. The optoelectronic interconnection layer under investigation employs optical channel waveguides and cascaded 3 dB 1-to-2 waveguide splitters in conjunction with surface-normal waveguide grating couplers. The planarization requirement for the optical interconnection layer required by multi-layer integration is fulfilled. Furthermore, the difficulties associated with the complicated 3-D multiple alignments are significantly reduced by the surface-normal fanout beams and the unique planarized device feature. An 1-GHz optical clock signal operating at 1.3 μm was transmitted through a 45 cm long polymer-based channel waveguide. Some new techniques to fabricate large-area optical channel waveguides and surface-normal waveguide grating couplers are also presented