Asymmetric Transmission and Wavefront Manipulation toward Dual-Frequency Meta-Holograms

Amplitude, phase, and polarization are three fundamental properties of electromagnetic (EM) waves, while the simultaneous control by conventional materials are usually associated with heavy and bulky designs. Here, a high-efficiency transmissive dual-frequency multifunctional metasurface that can enable efficient manipulation of the above three profiles at two distinct frequencies is proposed. The designed planar device with subwavelength thickness can not only achieve diode-like asymmetric transmission of linearly polarized EM wave, but also realize high performance low-crosstalk meta-holograms at dual frequencies. As a proof of concept, the subsequent experiments confirmed that the information (holograms) contained in the metasurface can be "read out" under the incidence of one polarization, while it was totally blocked under cross-polarized incidence. The average transmission coefficient and extinction ratio are larger than 84% and 58:1 that show great advances over previous counterparts. We believe the presented anisotropic dual-frequency metasurface is a powerful tool to achieve complete control of EM waves and has many potential applications in communication and encryption.