Modular Design for Versatile Broadband Polarizing Metasurfaces with Freely Switching Functions

Polarization is a fundamental property of electromagnetic waves that plays a key role in many physical phenomena and applications. Schemes to manipulate it have been revisited with the emergence of metasurfaces, which have brought multi-functionalities straightforwardly. However, this has come at the expense of design complexity that relies strongly on field theory. Here, we propose an ingenious strategy of modular design to construct subwavelength multifunctional polarization control devices. Chiral metasurfaces with different handedness are first proposed and regarded as the basic modules. The versatile polarization controller can thus be obtained with the combination of different modules. Our experiments demonstrate that the well-designed polarization controller possesses reconfigurable functionality; various broadband polarization and amplitude regulation functions with high efficiency including arbitrary linear polarization rotation, asymmetric transmission effect, neutral-density-like filter, polarization beam splitter, etc., can be readily realized just by changing the cascaded modules. The physical mechanisms of the versatile polarization controller and chiral metasurface modules are both guaranteed by the Fabry–Pérot-like resonances, which are theoretically verified via the transfer matrix method. We envision that the modular concept will be of great benefit to designing compact multifunctional polarization controllers.