| Summary: | This thesis describes the developments of guided-wave optical interconnects suitable for integration with printed circuit boards. The technology is based around direct laser writing of waveguides and other features in a newly developed multifunctional acrylate polymer system, using a He-Cd (325 nm) laser. It was demonstrated that, by writing with a laser spot having top-hat intensity profile, more sharply defined vertical and angled sidewalls could be achieved, compared to conventional methods using a Gaussian beam. Typical dimensions of the multimode waveguides were 50 x 50 J.lm, written with 50 J.lW of optical power with 100 J.lm/s scanning speed. The waveguide losses were measured, using the cut-back technique, to be -0.6 dB/em. A novel oil-immersion technique was developed to.overcome the limitations of refraction of the laser beam at the air / polymer inte~face and hence directly write 45° angled structures in the polymer. Metallised 45° out-of-plane mirrors were fabricated using these angled polymer structures and losses were measured to be ~ 0.8 dB per reflection. Successful coupling of optical signals between waveguides in different layers was also demonstrated in a double layer structure, in which the out-ofplane 45° mirrors provided the necessary optical connectivity. Direct laser writing was also employed to fabricate ~50 J.lm wide and 100 J.lm high polymer bumps for use in flip-chip bonding. Electroless gold plating was used to selectively metallise the polymer bumps and to produce electrical tracks on the substrate. Electrical resistances between the top of the bump and a lower metal pad were measured as less than ~5 ohms.
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