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Metasurfaces based on dielectric nanoantennas are an attractive platform to control light with sub-wavelength resolution and high efficiency [1]. Using this platform, a whole range of metasurface devices with different functionalities have been demonstrated in recent, with ever increasing efficiencies that are approaching industry standards [2]. In most cases, however, the realized devices are static, i.e., once they are fabricated, their functionality is fixed. It would be very appealing if, on the contrary, a single device could be reconfigured to perform any functionality on demand. To do so, tuning mechanisms to dynamically control the optical response of the nanoantennas must be explored. One promising way to do so is embedding them in liquid crystals (LC), which have a large birefringence and can be electrically driven – an important requirement for practical devices. Moreover, their technology is very mature due to their extensive used in the display industry.
In this talk, we will review our recent progress in electrical tuning of LC-embedded dielectric metasurfaces. We will show that the phase retardation experienced by a wave travelling through them can be controlled at will while maintaining high transmission levels, leading to highly efficient, tunable transmissive devices. We will show our experimental results operating at visible frequencies - around 660nm – by first showing tuning of metasurfaces as a whole to, subsequently, show that it is possible to address individual lines of nanoantennas to realize a tunable beam bending device.
References:
[1] A. I. Kuznetsov et al., “Optically resonant dielectric nanostructures”, Science 354, aag2472 (2016).
[2] S. Kruk and Y. S. Kivshar, “Functional Meta-Optics and Nanophotonics Governed by Mie Resonances”, ACS Photonics 4, 2638–2649 (2017).
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