Polarization Multiplexing Terahertz Metasurfaces through Spatial Femtosecond Laser-Shaping Fabrication

Terahertz (THz) metasurface has emerged as a powerful technique to fully modulate the wavefronts of THz radiation. To improve the information storage capability and enhance the encryption security of THz metasurface holograms, smart metasurface designs, and fabrications for polarization multiplexing are essential. In this study, two kinds of polarization multiplexing THz metasurfaces are fabricated through the slit-based spatial modulation of femtosecond laser. Controllable elliptical aperture arrays can easily and flexibly be fabricated on gold films by adjusting the width and position of the slit combined with the laser pulse energy. Based on the Pancharatnam–Berry phase and amplitude modulation, respectively, THz metasurfaces, with two independent target phases or amplitude profiles, are obtained. A variety of information can be processed under different polarization states through these THz metasurfaces. This method allows flexible and efficient customization of THz metasurfaces because of the high-speed fabrication and reproducibility as well as precise control of elliptical apertures location on the surface.