Constant frequency reconfigurable terahertz metasurface based on tunable electromagnetically induced...

Area of Science:

• Terahertz (THz) photonics
• Metamaterials and Plasmonics
• Graphene-based devices

Background:

• Electromagnetically induced transparency (EIT) creates sharp resonance features in the transmission spectrum.
• Metasurfaces offer tunable optical properties through structural design and material control.
• Graphene's tunable conductivity makes it a promising material for dynamic metasurface applications.

Purpose of the Study:

• To design and demonstrate a terahertz reconfigurable metasurface with a constant frequency EIT-like window.
• To investigate the control of EIT-like properties, modulation depth, and speed by reconfiguring graphene's Fermi energy.
• To explore the potential for miniaturized and high-performance terahertz modulators.

Main Methods:

• Design of a metasurface comprising two coupled single-layer graphene resonators (double big rings and double small rings).
• Numerical simulation and analysis of near-field coupling to induce an EIT-like phenomenon.
• Dynamic control of the Fermi energy of individual graphene resonators to tune EIT characteristics.

Main Results:

• An evident EIT-like transparency window with over 80% amplitude was achieved at 1.98 THz.
• The transparency window frequency remained constant while amplitude, modulation depth (up to 78%), and speed were actively controlled.
• The proposed structure demonstrated enhanced modulation performance and potential for miniaturization compared to existing metasurfaces.

Conclusions:

• The developed graphene metasurface enables constant frequency reconfigurable modulation in the terahertz domain.
• This work presents a viable method for creating high-performance, miniaturized terahertz modulators and optical switches.
• The static EIT window frequency offers advantages for specific terahertz device applications.