Dual-polarity dielectric cylindrical lens and spherical lens for visible light

In this paper, we propose a dielectric cylindrical lens and a dielectric spherical lens with dual polarity operating at visible frequencies. Composed of an array of nanofins with high aspect ratio as phase shifting elements, the designed dielectric dual-polarity lens have higher scattering efficiency and polarization conversion power than plasmonic dual-polarity lens. The phase variation from 0 to 2 pi is determined by adjusting the orientation angle of the individual nanofins according to the PB phase. By controlling the helicity of the incident circularly polarized light, the positive and negative polarity are interchangeable in one designed metalens. We demonstrate the broadband metalens possess a wavelength controllable focal length with incident wavelength from 488 to 740 nm. The dielectric dual-polarity metalens may open a new avenue for advanced research and applications in focusing and imaging devices, angular-momentum-based quantum information processing and integrated nano-optoelectronics.