Active liquid crystal-loaded metasurfaces for THz and IR applications

Buchnev, O., Wallauer, J., Walther, M., Podoliak, Nina, Kaczmarek, M., Zheludev, N.I. and Fedotov, V.A. (2014) Active liquid crystal-loaded metasurfaces for THz and IR applications. SPIE Photonics Europe '14, , Brussels, Belgium. 14 - 17 Apr 2014.

Abstract

One of the important steps towards practical application of the metamaterials is the implementation of an efficient active control over their optical response. This can be achieved by hybridising the fabric of these man-made photonic materials with naturally available functional media. Among such media liquid crystals possess arguably the largest and most broadband optical nonlinearity, while their properties can be readily controlled by light, temperature, electric and magnetic fields. Here we experimentally demonstrate active planar metamaterials (or metasurfaces) - artificially structured thin metal films loaded with liquid crystals, where the resonant response can be dynamically controlled both in terms of its magnitude and wavelength using externally applied electric field. The electric control has been implemented for THz and near-IR metasurfaces by engaging for the first time the in-plane switching of liquid crystals at micro- and nano-scale. As a result, it became possible to realise an optically thin large-area modulator of THz radiation with the absolute change in intensity and phase of correspondingly 20 % and 40 deg, achieved for a single pass transmission at only 20 V. For the near-IR metasurface we were able to bring the control voltage below 2 V demonstrating spectral tuning of its response by as larger as 100 nm.

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Contributors

Author: Nina Podoliak

Author: N.I. Zheludev

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