Determination of polarization states of electromagnetic waves plays a crucial role in photonic applications. However, it is very challenging to determine the polarization state of continuous terahertz (THz) waves. Here, a metasurface-like metallic waveguide array (MWA) is proposed to address this by measuring both the phase difference and amplitude ratio of its two orthogonal components based on generation and interference of polarization-multiplexing vortex beams. When a full-polarized THz wave passes through the MWA, its two orthogonal components will be converted into +1 st -and −1 st -order Bessel vortex beams, respectively. Their projection components in a proper polarized direction can interfere with each other, and their initial phase difference can be measured in real-time owing to its linear relationship with the azimuth of the dark fringe in interference patterns. The two Bessel beams can be further collected separately using a linear polarizer to obtain their amplitude ratio. Therefore, the polarization state of incident waves can be determined with both the phase difference and amplitude ratio. The proposed method enables a convenient polarization determination of continuous THz waves and has great potential for developing polarization-dependent investigations and applications in THz detection, communication, and sensing.

In terahertz (THz) photonics, a beam splitter is an important component. Although various THz beam-splitting devices using several principles have been proposed, the splitting ratio of existing designs is not adjustable. Here, a THz beam splitter with an adjustable splitting ratio is demonstrated using a metasurface integrated onto a prism. The metasurface excited by an evanescent wave can convert part of a linearly polarized incident wave into a cross-polarized wave and manipulate its phase simultaneously. As a result, the cross-polarized wave can pass through the interface, even if the incident angle is larger than the total internal reflection angle, while the co-polarized wave is reflected by the prism. The splitting ratio of the device can be adjusted from 4.56:1 to 0.63:1 by tuning the resonant response of the metasurface and varying the interval distance between the metasurface and the prism. The metasurface samples are fabricated using low-cost standard printed circuit technology, and the experimental results are consistent with the simulations. Therefore, the proposed beam splitter with a tunable splitting ratio is promising as a key component in the THz system.