Techniques are provided for single edge coupling of chips with integrated waveguides. For example, a package structure includes a first chip with a first critical edge, and a second chip with a second critical edge. The first and second chips include integrated waveguides with end portions that terminate on the first and second critical edges. The second chip includes a signal reflection structure that is configured to reflect an optical signal propagating in one or more of the integrated waveguides of the second chip. The first and second chips are edge-coupled at the first and second critical edges such that the end portions of the integrated waveguides of the first and second chips are aligned to each other, and wherein all signal input/output between the first and second chips occurs at the single edge-coupled interface.