Single-layered phase-change metasurfaces achieving efficient wavefront manipulation and reversible chiral transmission

Efficient control of the phase and polarization of light is of significant importance in modern optics and photonics. However, traditional methods are often accompanied with cascaded and bulky designs that cannot fulfill the ongoing demand for further integrations. Here, a single-layered metasurface composed of nonvolatile phase-change material Ge(2)Sh(2)Se(4)Te(1) (GSST) is proposed with tunable spin-orbit interactions in subwavelength scale. According to the spin-dependent destructive or constructive interference, asymmetric transmission fir circularly polarized incidence (extinction ratio > 8:1) can be achieved when GSST is in an amorphous state. Moreover, when GSST changes to crystalline state, reversed chiral transmission (extinction ratio > 12:1) can be observed due to the existence of intrinsic chirality. In addition, as the average cross-polarized transmitted amplitude is larger than 85%, arbitrary wavefront manipulations can be achieved in both states simultaneously based on the theory of Pancharatnam-Berry phase. As a proof of concept, several functional metasurface devices are designed and characterized to further demonstrate the validation of our design methodology. It is believed that these multifunctional devices with ultrahigh compactness are promising for various applications including chiroptical spectroscopy, EM communication, chiral imaging, and information encryption. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

Efficient control of the phase and polarization of light is achieved using a single-layered metasurface composed of the nonvolatile phase-change material GSST. The metasurface exhibits tunable spin-orbit interactions in subwavelength scale. It enables asymmetric transmission for circularly polarized light in the amorphous state and reversed chiral transmission in the crystalline state. The metasurface also allows arbitrary wavefront manipulations based on the theory of Pancharatnam-Berry phase. This study demonstrates the potential of ultra-compact multifunctional devices for applications such as chiroptical spectroscopy, EM communication, chiral imaging, and information encryption.