An assembly comprising first and second electronic devices and an optical resonator that optically couples an optical waveguide on the first electronic device to an optical waveguide on the second electronic device. In this way, optical proximity communication between the devices is possible. The electronic devices may be integrated circuit chips. A first portion of an optical resonator is disposed in a pit of the first device to optically couple the optical resonator to the first optical waveguide. A second portion of the optical resonator is disposed in a pit of the second device to optically couple the optical resonator to the second optical waveguide. Thus, the optical resonator optically couples the first optical waveguide to the second optical waveguide.