Active terahertz beam steering based on mechanical deformation of liquid crystal elastomer metasurface

Active metasurfaces are emerging as the core of next-generation optical devices with their tunable optical responses and flat-compact topography.Especially for the terahertz band,active metasurfaces have been developed as fascinating devices for optical chopping and compressive sensing imaging.However,performance regulation by changing the dielectric parameters of the integrated functional materials exhibits severe limitations and parasitic losses.Here,we introduce a C-shape-split-ring-based phase discontinuity metasurface with liquid crystal elastomer as the substrate for infrared modulation of terahertz wavefront.Line-focused infrared light is applied to manipulate the deflection of the liquid crystal elastomer substrate,enabling controllable and broadband wavefront steering with a maximum output angle change of 22°at 0.68THz.Heating as another control method is also investigated and compared with infrared control.We further demonstrate the performance of liquid crystal elastomer metasurface as a beam steerer,frequency modulator,and tunable beam splitter,which are highly desired in terahertz wireless communication and imaging systems.The proposed scheme demonstrates the promising prospects of mechanically deformable metasurfaces,thereby paving the path for the development of reconfigurable metasurfaces.

Reconfigurable and nonvolatile terahertz lithography-free photonic devices based on phase change films

High-performance terahertz(THz)devices with reconfigurable features are highly desirable in many promising THz applications.However,most of the existing reconfigurable THz elements are still limited to volatile responses,single functionality,and time-consuming multistep manufacturing procedures.In this paper,we report a lithography-free approach to create reconfigurable and nonvolatile THz components by exploring the reversible,nonvolatile,and continuous THz modulation capability of the phase change material Ge_(2)Sb_(2)Te_(5).As a proof of concept,THz gratings with significant Rayleigh anomalies and diffraction as well as ultrathin THz flat lenses with subwavelength and ultra-broadband focusing capabilities are designed and fabricated on ultrathin Ge_(2)Sb_(2)Te_(5)films using the presented photo-imprint strategy.Moreover,such a method can also be adopted to create more complex THz devices,such as Pancharatnam–Berry phase metasurfaces and grayscale holographic plates.With these findings,the proposed method will provide a promising solution to realize reconfigurable and nonvolatile THz elements.