Contents I. Summary
Fibre communications has benefitted tremendously from the miniaturization of components offered by silicon photonics. In order to be able to harvest fully these benefits, however, there need to be practical and efficient techniques for interfacing between fibre and integrated photonic systems. The two most widely adopted routes to achieving this are edge coupling and the use of waveguide gratings for directing light off-plane (or conversely capturing light to the waveguide from an out-of-plane direction). Even though grating couplers are often less efficient than edge coupling techniques, they offer advantages, such as tolerance to the fibre alignment and a direct route to wafer-scale testing. Their use also does not require any detailed facet preparation, which is necessary in the case of edge-coupled devices.
