Goal of the presented work is the development of an optical bus-coupler, which enables easy connection between two waveguides without interrupting the bus. It is possible to realize optical bus systems by connecting several modules onto one waveguide with a core-core-coupler. In this paper we present the concept of a bus-coupler, which is suitable for a bidirectional coupling with a definable ratio. In order to tune the coupling efficiency bended flexible planar waveguides are used, which are pressed onto the bus with a defined force adjusting the overlap area of the two coupling waveguides. We will introduce the manufacturing of the multimode waveguides on flexible substrates by photolithographic structuring. Furthermore, we present results of our investigations on the behavior of planar waveguides under bending in terms of optical losses and power distribution within the waveguide core. Based on the experimental results we will derive the requirements and design rules for the coupling element.