Matching the dual functions of vanadium dioxide metasurfaces through switchable Fabry-Perot structure

We propose a switchable VO2 metasurface design method, with which one can match the dual functions of switchable VO2 metasurface easily through optimization. In general, it is hard to match the two functions (possessing the same working band and high efficiency) by solely optimizing metasurface antenna. In our proposed method, by inserting a VO2 film into metasurface, a switchable Fabry-Perot cavity is generated, the working frequency band of dual functions can be matched easily by optimizing both antenna and Fabry-Perot cavities. In order to illustrate this method in detail, we designed two kinds of switchable VO2 metasurface, one possesses the switchable functions of absorption and lin-to-lin polarization conversion, the other one possesses switchable lin-to-lin and lin-to-cir polarization conversion. We believe this method will make it convenient for tunable metasurface design.