The demand of telecom operators for a 15 year lifetime of their systems is imposing a big challenge on component manufacturers. It means that also for optical connectors - which are used in large numbers in DWDM systems - the wear-out region must not be reached even after 25 years. However, how can it be shown that a connector will live for more than 25 years? Different approaches are possible: Collection of field data can supply information on the statistical failure rates at operating temperature. Accelerated aging tests (often simply called reliability tests) try to simulate aging under defined conditions. Our focus is on the reliability qualification according to the PAS (publicly available specification) IEC 62005-9-2 which is based on the co-work of Siemens with the connector manufacturers and assemblers Corning, Diamond, Huber+Suhner, Molex and TycoElectronics. This standard should now be overworked with the help of the results of the first common testing program which has recently been carried out by the Siemens ICN "Center for Quality Engineering".
The characterization of monomode passive polymer optical devices fabricated according to the POPCORN technology by methods originated from electron, ion and optical spectroscopy is summarized. Impacts of observed waveguide perturbations on the optical characteristics of the waveguide are evaluated. In the POPCORN approach optical components for telecommunication applications are fabricated by photo-curing of liquid halogenated (meth)acrylates which have been applied on moulded thermoplastic substrates. For tuning of waveguide material refractive indices with respect to the substrate refractive index frequently comonomer mixtures are used. The polymerization characteristics, especially the polymerization kinetics of individual monomers, determine the formation of copolymers. Therefore the unsaturation as function of UV-illumination time in the formation of halogenated homo- and copolymers has been examined. From different suitable copolymer system, after characterization of their glass transition temperatures, their curing behavior and their refractive indices as function of the monomer ratios, monomode waveguides applying PMMA substrates have been fabricated. To examine the materials composition also in the 6 X 6 micrometers <SUP>2</SUP> waveguides they have been visualized by transmission electron microscopy. With this method e.g. segregation phenomena could be observed in the waveguide cross section characterization as well. The optical losses in monomode waveguides caused by segregation and other materials induce defects like micro bubbles formed as a result of shrinkage have been quantized by return loss measurements. Defects causing scattering could be observed by convocal laser scanning microscopy and by conventional light microscopy.
Passive fibre-waveguide coupling is a promising alternative to expensive active coupling in single-mode fibre-optics. The idea to utilize replication techniques in transparent polymeric materials for waveguide and alignment structure fabrication has led to the SIGA-process (Silizium, Galvanik und Abformung) which allows a cost effective production of low loss polymer waveguides in the near IR. Major difficulties in passive fibre coupling are caused by the high lateral alignment accuracy (of about 1 micrometer) in fibre positioning. In the SIGA process, the exact position of the V- grooves relative to the waveguide trenches is defined by the etch mask for the silicon master wafer. The width of the V- grooves is determined by the KOH etching time. It is controlled precisely at various stages in the etching process by means of a microscope based piezo driven measurement system with a resolution better than 0.5 micrometer, thus allowing a final vertical precision of fibre positioning of 350 nm. In order to specify the capability of our technology we have measured the position of dozens of fibres glued into V- grooves. The result was that an amount of 55% of the fibre cores was closer than 1.5 micrometer to the waveguide centre. As the experience has shown, a two-step process for the fabrication of passively fibre coupled waveguides is necessary. First, the waveguides are produced by filling the waveguide trenches with an IR-transparent monomer and by polymerizing it using UV curing. The waveguides are inspected with visible and IR light by clamping a fibre ribbon mechanically into the integrated plastic V-grooves. In a second step the fibre ribbon is fixed irreversibly in the V- grooves. By that way we have reached an insertion loss of 3.5 dB at 1300nm and 1550nm for passively coupled 22mm single mode waveguides. Most of the losses are attributed to waveguide imperfections. More details concerning the coupling losses and the device performances will be reported at the conference.