Optically controlled chiral metasurface: Towards controllable bessel beams and holographic logic operation

Abstract

Chiral metasurfaces have expanded the control dimensions of traditional two-dimensional materials for manipulating beams, allowing for joint modulation of amplitude, phase, and polarization. As a result, they have attracted significant attention. This paper focuses on the tunable chiral metasurface applied in the THz regime. We propose an Ω-shaped metallic structure with an embedded photosensitive semiconductor material that allows for differential absorption of THz incident waves with various spins. The circular dichroic response of the designed chiral unit can be tuned by controlling the frequency and intensity of the pump light. The introduction of the PB (Pancharatnam-Berry) phase grants the chiral unit the ability to control the phase. In conclusion, the chiral unit achieves perfect control over the amplitude and phase of co-polarized reflected beams in the 7THz-9.7THz frequency range. In this paper, the aforementioned metasurface units are arranged into an array to achieve intensity-controllable Bessel beam and holographic logic operation. This proves the excellent performance of the designed chiral units in the THz regime. The optically controlled chiral metasurface proposed in this paper not only has application value in molecular control and optical computing but also provides a new approach for the THz chiral metasurface design.