Embedded Micro-Mirrors for Compact Routing of Multimode Polymer Waveguides

The limited scalability of high-speed electrical interconnects drives research on optical interconnect technologies. This work is concerned with compact polymer waveguide routing schemes for optical printed circuit boards (PCB). The developed embedded micro-mirrors are an integral part of the waveguide layer. The micro-structures that make up their bodies are fabricated directly onto the lower cladding of the waveguide by means of UV-laser patterning of a photosensitive resin. Vertical and 45°-tilted micro-structures are eventually used as in-plane and out-of-plane micro-mirrors, respectively. A wet-chemical deposition process is developed to apply the reflective metal layer selectively on the micro-structures. The fabrication processes are compatible to polymer waveguide and PCB manufacturing equipment. An electro-optical flex board is designed as basis for an optical transceiver module. Therein implemented are mechanical fiducial markers for adjustment-free alignment of the optical connector and the embedded out-of-plane micro-mirrors. The latter will vertically couple the light path from the laser- or detector-array to the polymer waveguide array. In a second part, an experimental approach to characterize the modal power coupling of light propagating in polymer waveguides is investigated. A modal power coupling matrix is thereby used to describe the relation between the input and output modal power distribution of a waveguide. The specific mode launch, required to control the input modal power distribution, is realized by an intensity- and a phase-controlling spatial light modulator (SLM). The modal power distribution at the end facet of the waveguide is analyzed by an approach based on optical Fourier transformation.