Dynamic display full-space spin-decoupled four-channel metasurface hologram based on photosensitive silicon

Full-space metasurfaces have attracted much interest due to their ability to simultaneously manipulate the reflection and transmission of incident waves. Manipulating multifunctional devices with greater degrees of freedom is an ongoing trend of development. The realization of full-space multi-channel holographic and its dynamic display in the terahertz region remains a challenge. In this paper, a two-resonator terahertz metasurface based on photosensitive silicon is proposed to achieve integrated reflective-transmissive functionality. The conjugate response of a unit structure consisting of two photosensitive silicon resonators is decoupled by introducing the propagation phase and the geometric phase. Four independent channels can be dynamically displayed simultaneously in full space at the same frequency, with their output modulated by both the polarization of the incident wave and the state of the photosensitive silicon. As an illustrative example, a four-channel dynamic display metasurface is designed to project three-bit polarization-encoded holographic images. In addition, by employing the convolution theorem and the generalized Snell's law, dynamic control of beam deflection and multi-beam generation is realized for four-channel holographic projections. This work not only proposes a generic strategy for realizing full-space multifunctional metasurfaces, but also has applications in miniaturized optical systems, high-capacity optical encryption and data storage.