Fig. 5: General inter-chip coupling architectures.
From: Advances in waveguide to waveguide couplers for 3D integrated photonic packaging
The images each show an example scenario of coupling between SOI waveguides (shown in red) on two separately fabricated chips, with (a) representing grating-to-grating coupling, (b) edge coupling, (c) evanescent coupling, (d) cantilever coupling, (e) free form coupling, and (f) optical wire bonding. The blue arrows indicate the direction of optical propagation before, during, and after coupling. Any pink structures in the images indicate components which are typically of a different material composition from the waveguides
