▎ 摘　　要

A methodology to design a multi-functional device (MFD) with switchable absorption and polarization conversion (PC) modes is proposed in this research. The methodology combines graphene absorbing metasurface (GAM) and polarization conversion metasurface (PCM) in one component. The key point is that the absorbing metasurface (AM) should be made completely by conductivity tunable material, such as graphene. The PCM can be constructed by fine metal. A prototype is designed to verify the designing methodology by stacking a layer of gold pattern PCM and two layers of GAM with fishnet shape patterns. In the PC mode, the chemical potentials of the two GAMs are mu(c1) = mu(c2) = 0 eV, then, the graphene layers act as thin dielectric layers, which can be treated as transparency. Thus, the PCM plays a leading role in the performances of the whole structure. Therefore, a linear polarized incidence is rotated by 90 degrees in the 2.10-3.13 THz (39.5% at 2.61 THz) with polarization conversion ratio (PCR) larger than 90%. In the absorption mode with mu(c1) = 0.5 eV and mu(c2) = 0.8 eV. the GAMs have strong surface plasmon-polaritons (SPPs), and they concentrate most of the incident power. which makes the GAMs dominate roles of the whole structure. Therefore, the incident power is dissipated in the GAMs. and the absorption rate is larger than 90% in the 1.30-3.01 THz (79.5% at 2.15 THz). The absorption band for absorption rate larger than 70% is 1.19-3.90 THz (106.7% at 2.54 THz). The design methodology is useful for the designing of components with switchable absorption and PC modes. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement