Demonstration of High Frequency Data Link on FR4 Printed Circuit Board Using Optical Waveguides

We report the development of a low cost, simple optical circuit board (OECB) using large core multi mode polymer waveguide on FR4 printed circuit board (PCB). The design of this OECB uses only a 45deg-ended waveguide to couple and decouple the optical signal directly between the optical devices and the waveguide. The 45deg mirror is formed using excimer laser process on a multi mode waveguide with temperature stability at reflow temperature. The optical waveguide is attached to a diced channel in the FR4 PCB using adhesive to form a completely planar circuit. This allows the laser diode and the photodiode to be assembled directly above the input and output of the waveguide using precision flip chip technology, which provides good alignment accuracy. This helps to increase the mechanical reliability of the circuit and minimize assembly requirements. Most importantly, all the electronic and optoelectronic devices used are commercially available components, the FR4 PCB fabrication process is standard process, the component assembly process is normal reflow process and the method is amenable for manufacturing. In the present publication, we report the details of the design, assembly process, high accuracy optical device attachment, performance characterization and testing results.