Fabrication of out-of-plane refractive concave and convex microlens arrays

Abstract

This paper describes a novel method to microfabricate out-of-plane convex and concave microlens array with optical axis parallel to the substrate for free-space optics. With wavelength selection and carefully controlled exposure dosage and development in the SU-8 lithography process, the satisfactory surface profiles and uniformity of pixels on the out-of-plane microlens array are obtained. With the optical axis of each pixel parallel with the substrate, these microlens arrays can be we can prealigned with other optical components, such as lens, prism, or mirror, in the mask design. This out-of-plane polymer microlens array can be pre-aligned with other optical components with no additional adjustment and assembly required, and therefore dramatically reduce the running cost and improve the quality and performance of the integrated optical system. Some preliminary results on pre-aligned fiber couplers and fiber bundle couplers fabricated with this out-of-plane microlens array are also presented.