March 2022
Spotlight Summary by Daniel Lopez
MEMS-tunable dielectric metasurface lens using thin-film PZT for large displacements at low voltages
Optical elements that offer fast, precise, and variable axial focus control are in great demand in many applications such as 3D displays, augmented reality, industrial inspection, and biomedical imaging. The most popular technologies used in designing varifocal optical elements include liquid crystals, acoustically driven fluid lenses, and mechanical devices such as galvo-mirrors and spatial light modulators. While all these technologies offer the prospect of miniaturization, integration with control electronics, and high-speed operation, microelectromechanical systems (MEMS) are particularly attractive because they could accomplish these requirements concurrently. In addition, MEMS structures have the distinct advantage of being ideal dynamic substrates to incorporate metasurfaces. While metasurfaces have demonstrated remarkable capabilities to manipulate light, their inherently static nature is an important limitation for their incorporation in reconfigurable optical systems.
In this work, a novel varifocal optical element is demonstrated by integrating dielectric metasurfaces onto thin-film piezoelectric-based MEMS. It consists of two co-axial metasurfaces whose relative distance is modulated with a piezoelectric film showing large mechanical deformations when low voltages are applied. The resulting varifocal lens exhibit a record tunability range of 250 µm at a wavelength of 1.55 µm and actuation voltages around 20 V.
These results establish a novel platform to produce complex tunable optical elements by merging metasurfaces with piezoelectric-based MEMS.
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In this work, a novel varifocal optical element is demonstrated by integrating dielectric metasurfaces onto thin-film piezoelectric-based MEMS. It consists of two co-axial metasurfaces whose relative distance is modulated with a piezoelectric film showing large mechanical deformations when low voltages are applied. The resulting varifocal lens exhibit a record tunability range of 250 µm at a wavelength of 1.55 µm and actuation voltages around 20 V.
These results establish a novel platform to produce complex tunable optical elements by merging metasurfaces with piezoelectric-based MEMS.
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Article Information
MEMS-tunable dielectric metasurface lens using thin-film PZT for large displacements at low voltages
Christopher A. Dirdal, Paul C. V. Thrane, Firehun T. Dullo, Jo Gjessing, Anand Summanwar, and Jon Tschudi
Opt. Lett. 47(5) 1049-1052 (2022) View: Abstract | HTML | PDF