Hybrid Metastructures Enabled by Dual-Frequency Liquid Crystals

Shortening the switching times of soft matter–based active metamaterials is one of the milestones to improve the functionality of frontier active devices. The frequency-convertible dielectric anisotropy of dual-frequency liquid crystal (DFLC) mixtures enables a fast response that can be tuned by an electrical signal with different frequencies. In this chapter, an introduction of double-frequency liquid crystals evidencing the functionalities of these systems and the advantage of their use to hybridize plasmonic metastructures is provided. Novel DFLC-based metastructures have been realized and characterized showing submillisecond response to electrical stimuli, about three orders of magnitude lower compared to systems loaded with standard nematic liquid crystals. A detailed numerical analysis of the E- and H-field distribution maps performed at the resonant frequencies of these systems confirms the experimental results. Furthermore, the DFLC-based hybrid metastructure reveals theoretically predicted switchable epsilon-near-zero (ENZ) properties. Finally, they provide an efficient platform for designing active broadband achromatic THz wave plates. These active metamaterials pave the way to numerous applications, including nonreciprocal magneto-optical effects, dielectric permittivity sensing, nonlinear ultrafast optical tuning, and self-assembled plasmonic systems.