This chapter is intended to give a description of different optical couplers used for the injection of light in a silicon waveguide. It starts with an introductory part, which provides a general overview of the coupling problem. The next four parts present the theory of the different couplers that use a butt coupling method like the 3D taper, the tips taper and the guide to guide coupler. The last three parts are devoted to the transverse coupling techniques which are the grating and the prism couplers.
Orobtchouk, R. (2006). On chip optical waveguide interconnect: The problem of the in/out coupling. Springer Series in Optical Sciences, 119. https://doi.org/10.1007/978-3-540-28912-8_10