Abstract: An exemplary integrated chip-scale laser assembly includes a chip-scale laser and a compact reference optical cavity optically coupled to an output of the chip-scale laser. The compact reference optical cavity is preferably a vacuum-gap Fabry-Perot (FP) reference cavity. Coupling to the Fabry-Perot cavity from a planar waveguide circuit via bonding may be achieved with metasurfaces and/or grating couplers. The cavity may be edge-coupled to a photonic circuit with a gradient index lens.