We proposed liquid ball lenses for optical coupling fabricated by parylene-on-liquid deposition (PoLD). A droplet of silicone fluid is
deposited onto hydrophobic circular step made by RIE etching and fixed by PoLD. PoLD enables us to fabricate a ball lens and a optical
waveguide on one wafer, so we can adjust the optical axes of ball lens and optical waveguide by photolithography process.
We fabricated up to 2.00-mm-diameter ball lens on 1.40-mm-diameter and 0.030-mm-high circular step. We confirmed that fabricated ball
lens could focus 0.5-mm-diameter laser beam light on 0.020-mm-diameter spot and couple laser beam light with the PoLD optical waveguide.