US Patent 10042131 Architecture for silicon photonics enabling wafer probe and test

Embodiments herein describe techniques for testing or aligning optical components in a photonic chip using a grating coupler. In one embodiment, the photonic chip may include an edge coupler and a grating coupler for optically coupling the photonic chip to external fiber optic cables. The edge coupler may be disposed on a side or edge of the photonic chip while the grating coupler is located on a top or side of the photonic chip. During fabrication, the edge coupler may be inaccessible. Instead of using the edge coupler to test the photonic chip, a testing apparatus can use the grating coupler along with a splitter to transfer optical test signals between an optical component in the photonic chip (e.g., a modulator or detector) and a test probe optically coupled to the grating coupler.