Adjustable strong circular dichroism based on a tricircular arc metasurface.

Circular dichroism has promising applications in biology, molecular chemistry, and other fields. The key to obtaining strong circular dichroism is to introduce symmetry breaking into the structure, which leads to a great difference in the response to different circularly polarized waves. Here, we propose a metasurface structure based on three circular arcs, which produces strong circular dichroism. The metasurface structure combines the split ring with the three circular arcs and increases the structural asymmetry by changing the relative torsional angle. The causes of the strong circular dichroism are analyzed in this paper, and the influence of metasurface parameters on it is discussed. According to the simulation data, the response of the proposed metasurface to different circularly polarized waves varies greatly, with absorption of up to 0.99 at 5.095 THz for a left-handed circularly polarized wave and a maximum circular dichroism of over 0.93. In addition, the incorporation of the phase change material vanadium dioxide on the structure allows flexible modulation of circular dichroism and modulation depths of up to 98.6%. The change of angle within a certain range has little effect on the structural performance. We believe that this flexible and angle robust chiral metasurface structure is suitable for complex reality, and large modulation depth is more practical.