Longitudinally variable 3D optical polarization structures

Abstract

Generation and manipulation of three-dimensional (3D) optical polarization structures have received considerable interest because of their distinctive optical features and potential applications. However, the realization of multiple 3D polarization structures in a queue along the light propagation direction has not yet been reported. We propose and experimentally demonstrate a metalens to create longitudinally variable 3D polarization knots. A single metalens can simultaneously generate three distinct 3D polarization knots, which are indirectly validated with a rotating polarizer. The 3D polarization profiles are dynamically modulated by manipulating the linear polarization direction of the incident light. We further showcase the 3D image steganography with the generated 3D polarization structures. The ultrathin nature of metasurfaces and unique properties of the developed metalenses hold promise for lightweight polarization systems applicable to areas such as 3D image steganography and virtual reality.

Multidimensional Encryption by Chip-Integrated Metasurfaces

“…In recent years, many previous endeavors have been focused on metasurface-based information multiplexing in order to expand information capacity. Specifically, through various optical parameters, including wavelength, − polarization, − orbital angular momentum, − wavevector direction, − and other active methods of manipulation, − metasurface devices provide the versatile capability to encrypt information into different operating near-/far-field channels. − However, manipulating only one single optical dimensional parameter still poses information leakage risks for nonauthorized parties to acquire concealed information. Therefore, utilizing multidimensional encoding by metasurface multiplexing is a promising trend for information security and capacity enhancement. − …”