Integrating a Semiconductor Nanowire Laser in a Silicon Nitride Waveguide

Silicon nitride (SiN)-based photonic integrated circuits (PICs) have the advantages of ultralow propagation loss, broad band transparency window, and CMOS-compatible fabrication process for promoting performances of optical telecom, spectroscopy, and sensing systems. However, the integration of conventional laser sources in SiN PICs is still challenged by complicated processes and low-volume manufacture. Here, we report a straightforward strategy to integrate laser sources in SiN PICs by deterministically postfabricating a SiN waveguide over a semiconductor nanowire (NW) laser, which was prelaid on a silicon oxide substrate. The laser emission from the waveguide-embedded NW was obtained, which was then coupled into the SiN single-mode waveguide and supported by the power division by an integrated beam splitter. The coupling efficiency between the NW lasing mode and the SiN waveguide mode was determined as 46.7%, which could be improved further to 83.6% by reducing the NW diameter based on numerical simulation. Benefiting from the postfabrication process, wide-band operation wavelength, and high waveguide-coupling efficiency of the NW laser, our work may provide a viable solution for large-scale integration of laser sources in SiN PICs.