Fig. 5: Thermally tunable CPL metalens.
From: Dynamic optical chirality based on liquid-crystal-embedded nano-cilia photonic structures
a Schematic of thermally tunable metalens. b Schematic of the metalens design, with the RH-cilia (red) forming the fine ring and the rest being LH-cilia (black). By designing a metasurface with a circular transmittance distribution, chiroptical focusing can be achieved. c Illustration of the metalens’ first order concentric ring. d The SEM image of the metalens’ first order concentric ring. RH-cilia structures are framed by red dashed line. Scale bar: 2 μm. e Detailed SEM image of the LH- and RH-cilia in the metalens. RH-cilia structures are framed by red dashed line, and LH-cilia structures are framed by black dashed line. Scale bar: 500 nm. f Experimental transmission spectrum of LH- and RH-cilia structures under LCP excitation. Orange line shows the CDlens spectrum. g Cross-sectional focal point intensity plots along the x-direction. h Cross-sectional focal point intensity plots along the z-direction. i−l Simulated and experimental focal point image. m Dynamic focusing switch of the metalens. The CDlens first decreases and then increases with temperature, during which the metalens initially loses its CPL focusing ability and then refocuses again. Insets show the optical image of the focal position. The metalens exhibits a reversed response to circular and linearly polarized light.
