Evaluation of the coupling performance and long-term stability of aerosol jet printed and photolithographic manufactured waveguides for asymmetric optical bus couplers

A novel coupling approach with specific coupling ratios depending on the coupling direction (optical bus to electrooptical device and vice versa) is presented. According to that, an asymmetric optical bus coupler (AOBC) is obtained, where a high amount of light is coupled from a device/module into the optical bus, whereas the ratio in the opposite direction is significantly smaller to keep enough energy in the bus for later coupling. This is realized without any filters by a specific bending of the waveguides. Hence, an up to four times higher coupling ratio in the module-to-bus direction is achieved compared to the opposite direction at the same junction. In contrast, current coupling schemes have a 1:1 coupling, waveguides are interrupted or filters are used. In this paper we investigate the influence of the waveguide manufacturing technology on the coupling performance. The standard photolithographic waveguides with rectangular cross-sections are compared to Aerosol Jet printed waveguides with circular segment cross-sections. Furthermore, we monitored the coupling for several days to get results on the stability. The results show a fluctuation of about ± 20 % for the printed waveguides and about ± 5 % for the photolithographic ones.