Inter-chip optical waveguide coupling analysis

Liu, Chun-Yu
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University of Delaware
In high-performance computing (HPC) systems, Moore's Law governs the density of integration and the switching speed of transistors on a chip. Moreover, optical interconnects are gradually becoming the majority of signal transmissions because of the higher bandwidth capacity, the low costs of polymer waveguides, and the immunity to electromagnetic interference. Vertical-cavity surface-emitting laser (VCSEL) advances have enabled architecture that connects chips via an opto-electronic circuit board and a bridge chip to affect high-density inter-chip interconnects. This thesis uses FDTD simulation software to optimize the coupling efficiency between the bridge chip and the opto-electronic circuit board with microlens arrays. The two parts of the design are separated by the coupling design from a VCSEL to a waveguide and the coupling design from a transmission waveguide to a receiver waveguide. Also, the coupling design from a transmission waveguide to a receiver waveguide is separated by two different tapered waveguide couplers (the 45o tapered waveguide coupler and the 37.3o tapered waveguide coupler). The two different designs of the tapered waveguide couplers are analyzed with the fundamental mode input and the multimode input. Therefore, we utilized simulations to analyze the coupling efficiencies and the alignment tolerances for those three designs.