Structures for an optical fiber groove and methods of forming a structure for an optical fiber groove. A photonics chip includes a substrate and an interconnect structure over the substrate. The photonics chip has a first exterior corner, a second exterior corner, and a side edge extending from the first exterior corner to the second exterior corner. The substrate includes a groove positioned along the side edge between the first exterior corner and the second exterior corner. The groove is arranged to intersect the side edge at a groove corner, and the interconnect structure includes metal structures adjacent to the first groove corner. The metal structures extend diagonally in the interconnect structure relative to the side edge of the photonics chip.