Polymer waveguides for telecom, telecom and sensor applications

LIGA, the process sequence of deep lithography, electroforming and molding has been used for the fabrication of polymer waveguide components with passive fiber-to-chip coupling. The variety of three-dimensional structures that can be, realized, the high precision that can be achieved and especially the possibility of cost-effective mass production make these components most relevant for telecom, datacom and sensor applications. A novel waveguide design for a singlemode Y-splitter acting at telecommunication wavelengths was developed and realized together with the coupling scheme described above. It shows superior performance to conventional layouts and is ideally adapted to st fabrication using LIGA. Combining LIGA with high precision diamond machining multi-level tools with the complementary waveguide and fiber alignment structures were fabricated. For the first time a very high precision of better than 1 mu m was achieved for heights and widths of all critical structures. A large number of molded parts was fabricated by hot embossing in PMMA. Detailed investigations proved that a reproducibility of better than 0.5 mu m for the replicated structures is possible. By filling in a suitable core material into the waveguide prestructures and fixing fibers in the fiber grooves, fully pigtailed Y-splitters have been fabricated. This is an easy passive fiber-to-Waveguide alignment with a significant reduction of manufacturing costs. First optical measurements on the samples showed an excess loss of 3.5 dB. Uniformity values were less than 0.6 dB and already meet Bellcore specifications. As another application of this fiber-to-waveguide coupling scheme a novel 4 x 4 star coupler for use in multimode optical bus systems is presented. First samples show an insertion loss of less than 9 dB and a uniformity better than 2 dB.