A new device developed by researchers can produce multiple distinct holograms depending on the wavelength of light used and the surrounding medium. The ability to store information that is only retrievable with the right set of keys could be further developed to design simple yet effective encryption devices.
The new metasurfaces give an immediate and simple readout of the environment surrounding the surface of the device.
The researchers show a device that shows a butterfly in dry conditions and a caterpillar in wet conditions. Both images are visible when 660-nm light is used. The metasurfaces can be tailored to work with a variety of pre-programmed conditions.
Di Falco said that their devices contribute to the worldwide effort to develop the physics and applications of photonic metasurfaces, which are one of the most versatile tools available to researchers.
There are multifunctional metasurfaces.
The new work is part of the Di Falco team's effort to develop metasurfaces that operate in the visible range and can be used for medical applications, which often involve wet environments.
Holographic metasurfaces are particularly interesting because they can be used to deliver complex information by producing images that can be immediately interpreted, without the need for additional layers.
Holographic metasurfaces can be used to create detailed images that depend on the light reflected or transmitted. The researchers used two types of meta-atoms to create holograms that show more than one image. One type of meta-atom only reflects light of a specific wavelength in dry conditions, while the other has high reflectivity only when a different wavelength is used.
Di Falco said that they designed a relatively simple meta-atom geometry that enhances the response of the holographic meta surface to the environmental conditions.
Demonstrating different images.
The researchers measured the efficiency of the metasurfaces in air and water. The contrast between the images was very good. Only one image was visible for each set of parameters, which showed two-tier information encoding.
The researchers want to create metasurfaces that distinguish between different media that have the same optical properties. This could be used to create holograms that show different images when exposed to different concentrations of a substance.
More information: Libin Yan et al, Two-Tier Manipulation of Holographic Information, Optics Express (2022). DOI: 10.1364/OE.456843 Journal information: Optics Express Citation: New metasurface-based device creates different images depending on light and environmental conditions (2022, May 17) retrieved 17 May 2022 from https://phys.org/news/2022-05-metasurface-based-device-images-environmental-conditions.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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