MEMS-tunable dielectric metasurface lens
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-μm 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 μm 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.
© 2018 The Author(s). Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received: 18 August 2017. Accepted: 24 January 2018. Published online: 23 February 2018. This work was supported by National Science Foundation award 1512266 and Samsung Electronics. A.A. and Y.H. were also supported by DARPA, and S.M.K. was supported as part of the Department of Energy (DOE) "Light-Material Interactions in Energy Conversion", Energy Frontier Research Center under grant no. DE-SC0001293. The device nanofabrication was performed at the Kavli Nanoscience Institute at Caltech. Author Contributions: A.A., A.F., and E.A. conceived the experiment. E.A., A.A., S.M.K., and Y.H. fabricated the samples. E.A., A.A., S.M.K., and M.F. performed the simulations, measurements, and analyzed the data. E.A., A.A., and A.F. co-wrote the manuscript. All authors discussed the results and commented on the manuscript. The authors declare no competing financial interests.
Submitted - 1712.06548.pdf
Published - s41467-018-03155-6.pdf