Cost effective method for spatially resolved characterisation of board level optical waveguides

The increasing bandwidth demand even on the printed circuit board level calls for alternative interconnection technologies. A promising approach is optical interconnection technology with integrated polymer waveguides. While light propagating through an integrated waveguide structure, the signal's attenuation is depicted as the main functional parameter. For this reason the integral optical loss is investigated with an attenuation measurement set-up. To additionally identify origin and determine the physics of failure a spatially resolved characterisation method would be beneficial. These methods measure the reflectivity as a function of distance. The paper gives an overview about existing spatially resolved reflectometry methods, discuss their advantages and drawbacks as well as designate OLCR as the superior measurement method for the given application. OLCR is the optical low-coherence reflectometry, which will be described in its principle. As an alternative to commercially available equipment a set-up, which uses free beam optics, will be presented. The prominent advantages of OLCR are thereby exploited to build cost-optimized realisation instead of a high performance equipment. By means of first measurement results the applicability of the OLCR set-up will be evaluated.