In this article, we give an overview of the development of an asymmetric optical bus coupler (AOBC) from the theoretical basis, the optical continuous wave, and bit rate performance to the implementation in a 3-D-Opto-MID package. The coupler allows for an interruption-free and bidirectional connection between two multimode waveguides, with different coupling ratios at the same node up to an aspect ratio of 5:1 depending on the coupling direction. For the first time, data transmission up to 12.5 Gbit/s is demonstrated with the AOBC, as well as the full implementation of the coupling element into a 3-D-Opto-MID package including an electrical test circuit.