Adjustable polarization converter of chiral nano array based on MIM structure

The invention provides an adjustable polarization converter of a chiral nano array based on an MIM structure. A chiral metal nano structure array comprises a plurality of MIM tetramer nano units which are periodically arranged; the MIM tetramer nano unit comprises two metal layer tetramers with the same thickness and a dielectric layer tetramer arranged between the two metal layer tetramers; each single-layer tetramer comprises four cuboid nanostructures which are arranged at intervals and have chiral response. Three metal/medium nano cuboids with the same size and one metal/medium nano cuboid with different sizes are utilized to form planar tetramers which are arranged at certain intervals and are longitudinally stacked to form an MIM tetramer chiral structure. Under irradiation of left-handed and right-handed circularly polarized light, optical rotation is generated due to the fact that refractive indexes of the structure for different polarized light are different, and tuning conversion of polarization and