Dynamic routing control through bends for Si sub-micrometer optical interconnects

Abstract

While optical interconnects is expected in the near future to provide the most definitive answer to the current bottleneck in further scale down of the electrical interconnects in VLSI circuits by replacing electrical interconnects altogether, it is currently hindered by the fact that traditional optical interconnect would usually require waveguides that are at least an order of magnitude larger than its electrical interconnect counterpart with a separation distance of few microns to avoid undesirable coupling. Plasmonics offer a solution to the waveguide dimension problem as the guiding mechanism in plasmonic waveguide depends on the coupling between electrons and photons and allow for using waveguides with sub-wavelength dimensions on the expense of greater losses. By using silicon with high concentration of excess carriers as the material of choice, we can acquire plasmonic mode in the near and mid infrared. In this paper we use slot waveguides with both intrinsic silicon with and without high excess carrier’s materials and investigate their transmission effectiveness over 90 degree bends. For silicon with high excess carrier concentration, the modes are plasmonic and allow for excellent performance in transmission through 90 degree bends. This enables dynamic control of routing over 90 degree bends by manipulating the number of free carriers through light excitation. The fact that the slot waveguide is used makes the optical interconnect has dimensions in the same order of magnitude as current electrical interconnects dimension.