Analysis and optimisation of bidirectional optical couplers in PCBs

Integrated optical waveguides on board level gain more interest with growing bandwidth. Due to limited space on board level, a new approach is to use bidirectional optical transmission on one single waveguide, to save space. As manufacturing technique we used an ion exchange process, as this has proven to be highly scalable and can be easily integrated into current PCB manufacturing processes. We developed an optical coupler for application in bidirectional optical transmission paths on a single waveguide. Due to the highly multimodal character of the structure, we applied ray tracing techniques to analyse the optical properties. By such means efficiency calculations as well as a transient analysis were possible. We determined important parameters of the structure for optimisation of the coupling efficiency.