Abstract

Diatomic metasurfaces designed for interferometric mechanisms possess significant potential for the multidimensional manipulation of electromagnetic waves, including control over amplitude, phase, frequency, and polarization. Geometric phase profiles with spin-selective properties are commonly associated with wavefront modulation, allowing the implementation of conjugate strategies within orthogonal circularly polarized channels. Simultaneous control of these characteristics in a single-layered diatomic metasurface will be an apparent technological extension.

Here, spin-selective modulation of terahertz (THz) beams is realized by assembling a pair of meta-atoms with birefringent effects. The distinct modulation functions arise from geometric phase profiles characterized by multiple rotational properties, which introduce independent parametric factors that elucidate their physical significance.

By arranging the key parameters, the proposed design strategy can be employed to realize independent amplitude and phase manipulation. A series of THz metasurface samples with specific modulation functions are characterized, experimentally demonstrating the accuracy of on-demand manipulation. This research paves the way for all-silicon meta-optics that may have great potential in imaging, sensing and detection.