High efficiency and high transmission asymmetric polarization converter with chiral metasurface in visible and near-infrared region

Abstract

Polarization manipulation of light is of great importance because it could promote development of wireless communications, biosensing, and polarization imaging. In order to use natural light more efficiently, it is highly demanded to design and fabricate high performance asymmetric polarization converters which could covert the natural light to one particular linearly polarized light with high efficiency. Traditionally, polarizers could be achieved by controllers with crystals and polymers exhibiting birefringence. However, the polarizers are bulky in size and the theoretical conversion efficiency of the polarizers is limited to 0.5 with unpolarized light incidence. In this paper, we propose a polarization converter which could preserve high transmission for one linearly polarized light and convert the orthogonal linearly polarized light to its cross-polarized with high transmittance based on a multi-layer chiral metasurface. Theoretical results show that normally incident y-polarized light preserves high transmittance for the wavelength range from 685 nm to 800 nm while the orthogonal normally incident x-polarized light is efficiently converted to the y-polarized light with high transmittance from 725 nm to 748 nm. Accordingly, for unpolarized light incidence, transmittance larger than 0.5 has been successfully achieved in a broadband wavelength range from 712 nm to 773 nm with a maximum transmittance of 0.58 at 732 nm.