Coding metamaterials have offered unprecedented degrees of freedom to manipulate electromagnetic waves in time and frequency domains in terms of various coding sequences, however, it is still challenging to realize dynamic coding metamaterials in the terahertz range. Here, we propose VO2-enabled transmission-reflection switchable coding terahertz metamaterials consisting of multilayered gold and VO2 patterns. The insulator-to-metal transition of VO2 leads to switch between the refractive and reflective scattering beams by changing the temperature. The four 2-bit elements are used to construct coding metasurface-based OAM generator with l = 1. Remarkably, the transmission-reflection switching functionality of the coding metasurface can be achieved at different frequencies. In addition, the novel designs in our work can achieve EM waves manipulation and provide a useful method to dynamically switch transmission-reflection response in the THz frequency regime.

Polarizers are an essential optical element for tailoring the polarization state of electromagnetic waves in a wide range of optical devices. Such polarizers, which exhibit a wide operating bandwidth and high performance, are attracting increasing attention, due to their extensive prospects for use in applications ranging from polarization imaging, to optical communications and detection, among others. However, achieving both broadband performance and ultra-high extinction ratio (ER), and that simultaneously, is still challenging in the design of effective polarizers. To tackle that demand, in this work, an Au-on-silica grating structure has been proposed as the basis of the design of a miniaturized high-efficiency polarizer that practically can cover the entire visible and near-infrared spectral ranges. The single-layer polarizer thus designed can show an ER of 60 dB in this spectral domain, and it has been shown that the geometrical parameters selected have a significant effect on the performance characteristics of the polarizer. Furthermore, an ER of ∼150 dB could be achieved merely by regulating the thickness of the grating to achieve the optimum performance. By integrating the high-performance polarizer proposed in this work with an optical fiber “meta-tip,” a refractive polarizer with a value of the ER of >45 dB, and that over the entire spectral domain considered, has been demonstrated. Such an approach offers an alternative route to achieving a broadband, powerful, and flexible processing polarizer design.