Mechanically-tuned optofluidic lenses for in-plane focusing of light

Abstract

In-plane lenses are desired for light manipulation within on-chip platforms. Such an in-plane lens can be achieved through optofluidic lens technologies that provide tunability of optical parameters through alterations to the shape or size of the lens. However, passive optofluidic lenses are often more desirable than active optofluidic lenses. In this work, we design a passive mechanically-tuned optofluidic lens. Tunability is brought about by placing a microdroplet between two substrate plates and varying the plate separation. We carry out analyses with an experimental optical setup and theoretical ray tracing. The experimental optical setup makes use of a fluorescent dye filler fluid to assist in the visualization and measurement of the back focal length. Ultimately, the sensitivity of the back focal length to a change in plate separation is shown, with strong agreement between experimental and theoretical analyses. It is envisioned that such a mechanically-tuned optofluidic lens will be used in a myriad of in-plane optical applications.