Batch assembly micro-ball lens array for Si-based optical coupling platform in free space

The paper presents novel concepts of batch fabrication of micro-ball lens a rray technology integrated on the silicon-based wafer which can improve the appropriate distance for optical fiber coupling. The silicon-based optical coupling platform consists of a self-parking framework (including flat-top ped mesa and intersection of two v-grooves) and micro-ball lens array for o ptical fiber coupling purposes. The structure of optical coupling platform is able to improve the distance between fiber and micro-ball lens and to in crease coupling efficiency. Optical measurement reveals an insertion loss b elow 2.5 dB with wavelength 635 nm in single-mode fiber. The micro-ball len s array is batch fabricated by polymeric material and thick photoresist, an d then bonded onto a flat-topped mesa that adjoins to the v-groove. The cor ner compensation offers a method to fabricate the flat-topped mesa in the i ntersection of two v-grooves. This fabrication process not only provides ac curate coupling distance between fibers and micro-ball lens, but also reduc es micro-assembly cost.