Single-step fabrication of a microlens array in sol–gel material by direct laser writing and its application in optical coupling

This paper presents a kind of inorganic–organic hybrid SiO2/ZrO2 sol–gel material successfully developed for use in a single-step fabrication of a refractive spherical microlens array (MLA). The single-step fabrication method employs direct laser writing technique to generate a designed spherical MLA on a layer of the sol–gel film. The method offers unique advantages over the conventional photoresist-based fabrication technology by eliminating the need for using a complex ion beam etching process and costly high-energy beam-sensitive grey scale mask. The measured results show that the microlenses have uniform dimensions, smooth surfaces, and strong focusing function. Furthermore, the fabricated MLA, as a coupler between a laser diode and a single mode fibre, has greatly improved the coupling efficiency between them.