Silicon dioxide photonic mems: Chip-to-chip alignment with positionable waveguides

THIS thesis describes the development of a positionable waveguide array realized in a silicon nitride / silicon dioxide (Si3N4 core / SiO2 cladding) photonic platform. The positionable waveguide array is the heart of a novel alignment approach for high precision multi-channel chip-to-chip interconnects. This alignment approach enables submicron accurate alignment of an Indium Phosphide (InP) Photonic Integrated Circuit (PIC) and a TriPleX interposer chip. Mechanically flexible waveguides with integrated alignment functionality are realized within the TriPleX interposer chip. Compared to competing alignment approaches, the proposed concept targets higher accuracy and precision and allows for an increased level of automation to lower assembly time and cost. The final alignment of the waveguides is achieved in two stages. In the first stage, both chips are flip-chip bonded on a common substrate. The result of this first stage is a coarse alignment of the waveguides of both chips, as well as mechanical fixation and electrical connection of both chips. In the second stage, integrated alignment functionality of the positionable waveguide array within the TriPleX interposer chip is used to optimally align the interposer waveguides with the waveguides of the InP PIC. Once aligned, the alignment function of the positionable waveguide array has served its purpose and the positionable waveguide array is mechanically fixed, providing an optimal alignment for the lifetime of the PIC.