Excimer laser ablation based microlens fabrication for optical fiber coupling purposes

Excimer laser ablation is a microfabrication technique suitable for surface structuring of polymers because of their high UV absorption and often non-thermal ablation behavior. Due to its non-contact and direct-write nature, laser ablation has the potential to allow insertion of micro-optical functionality by surface structuring in a late phase of a heterogeneous assembly. This in contrary to many of its competitors in the microfabrication technology. In this paper we investigate how the technique can be applied to fabricate microlenses in polymer materials and report on the present status of experimental results. Based on scanning a polymer surface with a pulsed excimer beam along well-chosen multiple concentric contours, microlenses of arbitrary shape can be realized. Optical performance and lens surface quality are evaluated by imaging experiments, scanning electron microscopy and profilometer measurements. One particular application of microlenses deals with enhancing the optical power transfer efficiency in coupling from, to or between single mode optical fibers. By attaching a dedicated thin polymer layer on a fiber end, one is able to put a microlens on the fiber facet using excimer laser ablation. Current status of the experimental results will be discussed.