Researchers combine piezoelectric thin film and metasurfaces to create lens with tunable focus:
Tunable focusing is a desired property in a wide range of optical imaging and sensing technologies but has tended to require bulky components that cannot be integrated onchip and have slow actuation speeds. Recently, integration of metasurfaces into electrostatic micro-electromechanical system (MEMS) architectures has shown potential to overcome these challenges but has oﬀered limited out-of-plane displacement range while requiring large voltages. We demonstrate for the first time, to the best of our knowledge, a movable metasurface lens actuated by integrated thin film PZT MEMS, which has the advantage of oﬀering large displacements at low voltages. An out-of-plane displacement of a metasurface in the range of 7.2 µm is demonstrated under a voltage application of 23 V. This is roughly twice the displacement at a quarter of the voltage of state of the art electrostatic out-of-plane actuation of metasurfaces. Using this tunability, we demonstrate a varifocal lens doublet with a focal shift of the order of 250 µm at the wavelength 1.55 µm. The thin-film PZT MEMS-metasurface is a promising platform for miniaturized varifocal components.
More information: Christopher A. Dirdal et al, MEMS-tunable dielectric metasurface lens using thin-film PZT for large displacements at low voltages, Optics Letters (2022). DOI: 10.1364/OL.451750