This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new technique for controlling optical components with light could help usher in a generation of high-efficiency signal-processing technology that could drive futuristic applications such as holographic video. Physicists at the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS) at ANU have developed a way to make static devices dynamically tunable with light, an important capability for flexible, powerful light-based technology known as photonics.
They did this by embedding a metasurface, which is conventionally static, in liquid crystals mixed with a photoresponsive dye, said project leader Dr. "We can change the optical response of the metasurface optically—without any electrodes, magnetic components or heating elements, just using light," said Izdebskaya, who is in the Department of Fundamental and Theoretical Physics and is a member of TMOS. "It's entirely reversible, which has been a challenge until now." Computer chips based on photonics promise faster, more energy-efficient signal processing with less noise than electronic chips.
However, they lack some signal-processing functions. The new technique could provide some of that missing functionality, such as optical switching and dynamic beam shaping. Metasurfaces can generate optical effects that natural materials cannot.
They are built from surface arrays of nanoscopic shapes smaller than the wavelength of light. Their effects depend on the difference in refractive index between the metasurface itself (in this case, a dielectric material called hydrogenated amorphous silicon) and the surrounding medium, such as air. The refractive index of air is not easily changed.
But if the metasurface is covered by a liquid crystal whose refractive index can be changed, its behavior can be dynamically controlled. The TMOS team had previously pioneered the use of magnetic fields to control a metasurface filled with liquid crystals. But their ultimate goal was to move away from electromagnetic methods and develop optical control.
Andrey Iljin of the University of Münster, Germany, provided the missing piece of the puzzle. A dye specialist, Iljin collaborated with the team to add the photoresponsive dye methyl red to a liquid crystal. Methyl red is a large dye molecule that can switch between straight and bent forms when illuminated by green light (wavelength 532 nm), depending on the polarization of the light.
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