Fabrication of Microlens Arrays on Layered Polymers*

Microlens arrays have numerous applications they offer in many areas, such as optical communication, optical computing, and for collecting light power needed in photovoltaics and laser beam shaping. Microlens made out of polymer Gradient Refractive INdex (GRIN) materials can eliminate spherical aberration, which is generally reduced by designing the lens with aspheric surfaces. At the micro and nano scale, aspheric surfaces are hard to fabricate. The goal of this project was to fabricate arrays of microlens on GRIN polymer materials by photolithography and plasma dry-etching, creating lenses with axially-terminating edges. Lenses produced in this manner ideally correct for spherical aberration. We were able to successfully fabricate microlens arrays in multilayer polymer, though dry etching with Ar/O$_{2}$ gas. The lenses were characterized using atomic force microscopy and scanning electron microscope. The diameters of these microlenses ranged from 20 -- 80 $\mu $m, a height of 3-5 $\mu $m and an estimated focal length of about 50 $\mu $m. In this presentation, methods for improving out fabrication process as well as optically characterizing the microlens arrays will be discussed.