UV-curable resin microlenses on optical pillars for optical interconnect

A unique combination of pillar and microlens is demonstrated to enable easy coupling between VCSEL layers and a multi-layer/channel optical printed wiring board. A number of uniform pillars having a microlens on the top were fabricated on a substrate using UV-curable resin by mask-transfer self-written waveguide and dipping methods. Ray-trace analysis indicated that the focusing characteristics could be controlled by adjusting the pillar height and the microlens radius of curvature. Tolerance coupling efficiency between pillar height and microlens radius of curvature is acceptable. Light propagation measurements showed that uniform power was obtained from all top microlenses of the 3 × 4 pillar array on a slide glass. Studies of the reproducibility of microlens-on-pillar fabrication using the dipping method show a positive outcome. As a result, optical coupling efficiency is expected to be improved in optical interconnect applications.