Ultra-high-efficiency circularly polarized reflector based on the dislocated double rectangle arrays

The chiral lasers that can directly generate the circularly polarized light have important applications in a variety of fields, such as optical communications, biomedicine, materials processing, and optical measurements, and they are rapidly becoming an offshoot of the new generation of smart optoelectronic devices. However, the performance of current circularly polarized lasers is still limited by the effective design of chiral nanostructures, and their circular dichroism (CD) generally does not exceed 5%. With the powerful optical modeling capability of the COMSOL Multiphysics platform, we innovatively introduce two dislocated rectangular blocks to break the spatial symmetry of the metasurface and obtain a huge chirality (CD > 95%). This is then combined with a cylindrical array to form a Fabry–Pérot (FP) resonant cavity corresponding to a typical optical ternary system, which pushes the peak reflectivity of the cascaded metasurface to 99.6%. Our designed chiral cascade metasurfaces simultaneously satisfy the demanding requirements of high reflectivity and large circular dichroism, and are expected to replace the conventional multilayer distributed bragg reflectors (DBRs) in VCSELs, contributing to the further development of miniaturized chiral lasers.