MEMS-tunable dielectric metasurface lens

TL;DR

This paper introduces MEMS-tunable dielectric metasurface lenses that enable compact, fast, and adjustable varifocal optical systems with potential applications in 3D imaging and microscopy.

Contribution

It demonstrates a novel MEMS-integrated metasurface doublet capable of significant tunability and fast scanning, advancing reconfigurable flat optics.

Findings

Over 60 diopters change in optical power with 1-um movement

Potential scanning frequency of a few kHz

Compact microscopes with large FOV and axial scanning

Abstract

Varifocal lenses, conventionally implemented by changing the axial distance between multiple optical elements, have a wide range of applications in imaging and optical beam scanning. The use of conventional bulky refractive elements makes these varifocal lenses large, slow, and limits their tunability. Metasurfaces, a new category of lithographically defined diffractive devices, enable thin and lightweight optical elements with precisely engineered phase profiles. Here, we demonstrate tunable metasurface doublets, based on microelectromechanical systems (MEMS), with more than 60 diopters (about 4%) change in the optical power upon a 1-um movement of one metasurface, and a scanning frequency that can potentially reach a few kHz. They can also be integrated with a third metasurface to make compact microscopes (~1 mm thick) with a large corrected field of view (~500 um or 40 degrees) and fast axial scanning for 3D imaging. This paves the way towards MEMS-integrated metasurfaces as a platform for tunable and reconfigurable optics.