Characterization of passive polymer optical waveguides

The characterisation of monomode passive polymer optical devices fabricated according to the POPCORN technology bymethods originated from electron, ion and optical spectroscopy is summarized. Impacts of observed waveguide perturbationson the optical characteristics ofthe waveguide are evaluated.In the POPCORN approach optical components for telecommunication applications are fabricated by photo-curing of liquidhalogenated (meth)acrylates which have been applied on moulded thermoplastic substrates. For tuning of waveguidematerial refractive indices with respect to the substrate refractive index frequently comonomer mixtures are used. Thepolymerisation characteristics, especially the polymerisation kinetics of individual monomers, determine the formation ofcopolymers. Therefore the unsaturation as function of UV-illumination time in the formation of halogenated homo- andcopolymers has been examined. From different suitable copolymer systems, after characterisation of their glass transitiontemperatures, their curing behaviour and their refractive indices as function of the monomer ratios, monomode waveguidesapplying PMMA substrates have been fabricated. To examine the material composition also in the 6 x 6 jtm2 waveguidesthey have been visualised by transmission electron microscopy. With this method e.g. segregation phenomena could beobserved in the waveguiding copolymer with features in the 100 nm range. Secondary ion mass spectrometry has been usedfor waveguide cross section characterisation as well. The optical losses in monomode waveguides caused by segregation andother material induced defects like micro bubbles formed as a result of shrinkage have been quantisized by return lossmeasurements. Defects causing scattering could be observed by convocal laser scanning microscopy and by conventionallight microscopy.Keywords: integrated optics, polymer waveguide, halogenated acrylates, halogenated methacrylates, convocal scanninglaser microscopy, transmission electron microscopy, SIGA, POPCORN