Search

Printing polymer optical waveguides by means of combined printing processes has proven to be a challenging but effective way of producing waveguides with a loss less than 0.3dB/cm. In order to evaluate the optical performance of the produced waveguides, optical simulations have been carried out. In this work we show the influence on the optical performance by simulating droplets and enclosures in multimode waveguides with a proprietary raytracing algorithm. Critical waveguide parameters such as width and height variation will be evaluated. Finally, experimentally achieved optical performance is presented and compared with the simulation result.

The combination of hybrid interconnection technology on ceramic as a carrier for the RF-electronics with excellent heat management and stereolithographic printing for 3D structures is a novel approach to achieve 3D-Opto-MID parts and, furthermore, to include mechanical properties. By directly printing polymers onto aluminum-oxide substrate (including an electrical circuit), brings together the advantages of both technologies. Using additive manufacturing makes this process suitable for small- to mid-scale productions with a very high design freedom. To analyze the adhesion between Al2O3 substrate and printed polymers, we compare six different resins according to the minimal structure length and the adhesion on the substrate. A longer exposure time of the first layer (burn-in time) leads to sufficient adhesion of the print on the ceramic substrate. To realize smaller adherent structures, longer burn-in times are needed. In a shear test, the forces to lift off the prints from the substrate are measured. The experiments reveal correlation between shear force and contact area with little variance. Based on this evaluation, choosing materials for future applications is easier and design rules can be determined. Furthermore, we present the application of flexible optical waveguides onto the 3D substrate (which will be directly printed in the future), as well as the passive alignment of laser and photodiode in this article. In a first test, we were able to prove the functionality of the 3D-Opto-MID package by launching the waveguide with the applied laser and measuring the current at the photodiode.

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.

In our work an optical bus-coupler is proposed, which enables easy bidirectional connection between two waveguides without interrupting the bus using a core-to-core coupling principle. With bended waveguides the coupling ratio can be tuned by adjusting the overlap area of the two cores. In order to ensure large overlap areas at short coupling lengths, the waveguides have rectangular cross sections. To examine the feasibility of this coupling concept a simulation was performed, which is presented in this paper. Due to multimode waveguides, used in short range data communication, a non-sequential ray tracing simulation is reasonable. Simulations revealed that the bending of the waveguide causes a redistribution of the energy within the core. Small radii push the main energy to the outer region of the core increasing the coupling efficiency. On the other hand, at excessive lowered bend radii additional losses occur (due to a coupling into the cladding), which is why an optimum has to be found. Based on the simulation results it is possible to derive requirements and design rules for the coupling element.