Spin-enabled terahertz quasicrystal metasurface for orbital angular momentum engineering

Area of Science:

• Photonics and Metamaterials
• Condensed Matter Physics

Background:

• Quasicrystals possess long-range order without translational symmetry, featuring high-order rotational symmetry distinct from conventional crystals.
• Metasurfaces offer powerful platforms for manipulating light, particularly for orbital angular momentum (OAM) spatial control of terahertz (THz) beams.

Purpose of the Study:

• To numerically demonstrate a terahertz (THz) vortex beam emitter utilizing silicon quasicrystal metasurfaces.
• To explore the selective excitation and flexible control of orbital angular momentum (OAM) modes using quasicrystal metasurfaces.

Main Methods:

• Implementation of the Penrose tiling arrangement with fivefold rotational symmetry.
• Numerical simulations and theoretical analyses of the quasicrystal metasurface's performance.

Main Results:

• Efficient realization of both first- and higher-order vortex beams in the THz regime.
• Demonstration of favorable broadband response and structural robustness.
• Exploitation of the non-periodic nature for enhanced wavefront manipulation and reduced micro-atom density.

Conclusions:

• Silicon quasicrystal metasurfaces provide enhanced design freedom for highly integrated, multifunctional optical devices.
• The proposed metasurface enables selective excitation and flexible control of OAM modes, breaking traditional design constraints.
• Promising applications in optical communications, quantum information processing, and micro-nano optics are anticipated.