On-chip optical interconnects with compact and low-loss light distribution in silicon-on-insulator rib waveguides

The possibility of on-chip optical interconnects using rib waveguides on silicon-on-insulator substrates (SOI) is demonstrated. It is shown that ultrasmall (<0.4 μm²) rib waveguides intrinsically combine the advantages of low measured propagation losses (<0.5 dB/cm), negligible crosstalk between waveguides and no crosstalk at right angle crossings. A set of devices have been studied using finite difference time domain analysis to realize 90° change of direction and beam splitting, including fully etched mirrors and 1×2 star couplers of 14 ×8-μm area. Considering the compactness and efficiency of all studied devices, it is shown that a compact and low-loss light distribution can be achieved in an integrated circuit toward at least 64 photodetectors with SOI rib waveguides that fully meets requirements of minimal power to be delivered to receiver circuitry.