Edge Couplers with relaxed Alignment Tolerance for Pick-and-Place Hybrid Integration of III-V Lasers with SOI Waveguides

摘要

We report on two edge-coupling and power splitting devices for hybridintegration of III-V lasers with sub-micrometric silicon-on-insulator (SOI)waveguides. The proposed devices relax the horizontal alignment tolerancesrequired to achieve high coupling efficiencies and are suitable for passivelyaligned assembly with pick-and-place tools. Light is coupled to two on-chipsingle mode SOI waveguides with almost identical power coupling efficiency, butwith a varying relative phase accommodating the lateral misalignment betweenthe laser diode and the coupling devices, and is suitable for theimplementation of parallel optics transmitters. Experimental characterizationwith both a lensed fiber and a Fabry-P\'erot semiconductor laser diode has beenperformed. Excess insertion losses (in addition to the 3 dB splitting) taken asthe worst case over both waveguides of respectively 2 dB and 3.1 dB, as well asexcellent 1 dB horizontal loss misalignment ranges of respectively 2.8 um and3.8 um (worst case over both in-plane axes) have been measured for the twodevices. Back-reflections to the laser are below -20 dB for both devices withinthe 1 dB misalignment range. Devices were fabricated with 193 nm DUV opticallithography and are compatible with mass-manufacturing with mainstream CMOStechnology.