Fig. 9
Polarization-dependent imaging applications of metalenses. (a) SEM images of a plasmonic lens on an ITO-coated glass substrate with negative polarity (upper panel) and positive polarity (lower panel) for an incident right circularly polarization (RCP) light [93]. Scale bar: 1 mm. (b) Schematic illustration of imaging for metalens used as a convex lens and a concave lens. SEMs of the grating (object) at 810 nm without the metalens (top), a magnified image for RCP incident beam with a magnification of 1.45 (middle) and a reduced image for LCP incident beam with a magnification of 0.87 (bottom) [93]. The scale bar is 50 mm. (c) Upper panel: the focusing properties of the same metalens can be switched between a convex lens and a concave lens by controlling the helicity of the incident light. Lower panel: SEM image and phase distribution of the fabricated dual-polarity plasmonic lens with a focal length of 80 μm [94]. (d) Experimental demonstration of imaging [94]. (e) The building block of the chiral lens consists of two nanofins on a glass substrate. Upper right panel: SEM image of chiral lens. Scale bar: 600 nm. Lower panel: Imaging principle of the chiral lens where LCP and RCP light from the same object [95]. (f) Images of the beetle obtained by the chiral lens on the color camera and images of a one-dollar coin under green LED illumination [95]. (g) Optical microscope image of the grating sample shows Fresnel zones owing to the weak, polarization independent lensing effect imposed on top of the metagrating. Inset: metasurface consists of subwavelength, form-birefringent TiO2 pillars array. Right panel: Imaging system packaged into a portable prototype and the essential part of the camera [96]. (h) A plastic ruler and spoon with the information of Stokes vectors are photographed with the camera [96]