Optical modules and methods for making optical modules are described. In one embodiment, an optical module includes a substrate assembly including a photonic chip mounting region, and a groove extending towards the photonic chip mounting region. A waveguide is disposed within the groove. A plurality of spacers is on the chip mounting region, each spacer having a predetermined height. A photonic chip is placed on the plurality of spacers and above the chip mounting region, and an optical coupler is between the photonic chip and the waveguide.