Broadband all-dielectric meta-lenses with terahertz full-Stokes polarization detection behavior

Polarization is a fundamental characteristic of electromagnetic (EM) waves, and accurately determining the polarization state is crucial for spectral imaging and information processing. However, implementing broadband polarization detection in the terahertz (THz) range poses significant challenges when employing conventional optics. This paper proposes and experimentally evaluates a broadband polarization detection strategy using all-dielectric metasurfaces. By employing the technique of circular polarization multiplexing, the proposed approach allows for the generation of a focus that contains the incident polarization information at a predetermined plane. When a fully polarized THz beam interacts with the proposed design, its two orthogonal circularly polarized components weighted equally and simultaneously converge at designed spatial coordinates. Subsequently, by capturing the complex amplitude at the target pixel, the full-Stokes parameters and equations of the polarization ellipse corresponding to the incident polarization state can be extracted in real time. Further optimization of the phase encoding profile embedded within the orthogonal circular polarization channel can eliminate the chromatic aberrations within the target bandwidth, thereby achieving broadband THz polarization detection. This method facilitates the determination of polarization states across the broadband THz spectrum and holds significant promise for advancing polarization-related research in areas such as detection, communication, and sensing.