Asymmetric transmission polarization conversion of chiral metamaterials with controllable switches based on VO2

In this work, a controllable switch-type chiral metamaterial (SCMM) is proposed to realize asymmetric transmission (AT) polarization conversion. This function is realized by the phase change characteristics of vanadium dioxide (VO2). When VO2 is in an insulating state, the SCMM realizes AT and the conversion from line polarization to cross polarization. Numerical simulation results show that in the frequency bands of 1.67-1.74 THz and 1.86-2.05 THz, extremely low ellipticity, 90 degrees polarization azimuth and higher than 90% polarization conversion rate (PCR) are achieved. And the AT parameter can be as high as 0.87. When VO2 is in a metallic state, the function is turned off. By observing the distribution of surface current, the physical mechanism of AT polarization conversion is explained. Finally, by comparing the surface current distribution and chirality parameters in the two states, the internal mechanism of realizing the switching function is explained.

Automated summary

A controllable switch-type chiral metamaterial has been proposed to achieve asymmetric transmission (AT) polarization conversion using the phase change characteristics of vanadium dioxide (VO2). The function achieves extremely low ellipticity, 90 degrees polarization azimuth, and higher than 90% polarization conversion rate in specific frequency bands. The physical and internal mechanisms of the switching function are explained through surface current distribution and chirality parameters comparison.