High Density Optical Interconnects

The proposal described herein presents a novel Mode-Division-Multiplexing (MDM) to realize waveguide arrays with subwavelength waveguide pitches. Waveguide arrays are usually designed with waveguide pitches of about a few wavelengths in order to avoid cross-talk. Multiple-Input-Multiple-Output (MIMO) enabled MDM has been used to enhance data rate in multimode fibers beyond their dispersion limit. While MIMO in multimode fibers has been practically limited to two channels due to the difficulty of efficient accessing different modes at the input and output, a carefully designed fan-out structure will allow access to the super-modes in a waveguide array that has significant coupling between adjacent waveguides. While the MDM technique tackles the issue of the cross-talk between the waveguides in the array, in the case of waveguide crossing, the insertion loss and cross-talk to the crossing waveguide can be prohibitive without any special designs. Thus, we also propose an efficient technique for waveguide array crossing with 0.01dB loss and <-40dB crosstalk per crossing. Given the potential of the plasmonic waveguides for various data processing and sensing applications, we will present an efficient strip-plasmonic waveguide mode converter (loss<0.02dB) that can enable novel devices such as low-insertion loss compact plasmonic modulators.