Embodiments herein describe optical assemblies that use a spacer element to attach and align a laser to a waveguide in a photonic chip. Once aligned, the laser can transfer optical signals into the photonic chip which can then perform an optical function such as modulation, filtering, amplification, and the like. In one embodiment, the spacer element is a separate part (e.g., a glass or semiconductor block) that is attached between the photonic chip and a submount on which the laser is mounted. The spacer establishes a separation distance between the photonic chip and the submount which in turn aligns the laser with the waveguide in the photonic chip. In another embodiment, rather than the spacer element being a separate part, the spacer element may be integrated into the submount.