Terahertz polarization detection based on the mode analysis of longitudinally polarized vortices

Polarization detection of terahertz waves is essential for applications of terahertz waves in communication, imaging, and other fields. Here, we propose a novel terahertz polarization detection approach via the mode analysis of transmitted longitudinally polarized vortex field. By finely designing the phase profiles of the proposed all-silicon metasurface, we establish a connection between the generated longitudinally polarized vortices and the polarization parameters of the incident field. Complete polarization parameters are obtained by analyzing the intensity, phase, and mode purity of the longitudinally polarized vortex field. The comparisons between the detected polarization states and the incident states prove the accuracy of the proposed metasurface for polarization detection. Such metasurface polarization detection scheme may further promote the application of terahertz technology.