Three-in-one polarization detector enabled by metasurface

Abstract In the field of biomedicine, the detection of target analytes imposes requirements on polarization information detection and sensitivity. It necessitates non-destructive analysis of proteins and DNA. The combination of dielectric geometric metasurface with terahertz (THz) vortex beams present new opportunities for biomedical sensing. In this work, we employ simulation to demonstrate a novel methodology that integrates off-axis dual-focus with vector vortex beams (VVB). Moreover, the metasurface-based method provides potential solutions for miniaturized polarization detection. The capability of polarization detection is evaluated using different polarization states at three different focal planes. Specifically, the ellipticity and handedness of incident THz waves can be determined by the electric field intensity ratio of the two off-axis focused spots. The major axis direction of linear polarization waves can be determined by extracting the azimuth of the VVB. It is worth mentioning that higher-order VVB, benefiting from its high angular resolution characteristics, exhibits enhanced sensitivity in determining the direction of major axes. Our proposed scheme offers potential applications for THz communications, medical imaging, security detection and remote sensing.