Dual Toroidal Dipole Resonance Metamaterials under a Terahertz Domain

Area of Science:

• Metamaterials
• Electromagnetism
• Nanotechnology

Background:

• Metamaterials offer unique electromagnetic properties not found in natural materials.
• Toroidal dipole (TD) resonances are crucial for advanced electromagnetic applications.
• Achieving dual TD resonances with tunable quality factors (Q) is a significant challenge.

Purpose of the Study:

• To propose and fabricate a flexible metamaterial (MM) capable of dual toroidal dipole (TD) resonances.
• To investigate the coupling effects and underlying mechanisms responsible for TD resonances.
• To demonstrate the tunability of TD resonance frequencies and quality factors (Q).

Main Methods:

• Fabrication of a flexible planar metamaterial using U-shaped split ring resonators (USRRs).
• Experimental measurements and numerical simulations to analyze electromagnetic responses.
• Quantitative calculation of electric dipole, magnetic dipole, electric circular dipole, and TD powers.

Main Results:

• Synchronous observation of low Q (~1.82) and high Q (~10.31) TD resonances at different frequencies.
• Tuning of TD resonance frequencies by adjusting the distance between coplanar USRRs.
• Identification of inductance-capacitance (LC)-induced and dipole-induced TD resonances due to USRR interactions.

Conclusions:

• The proposed U-shape-modified metamaterial successfully achieves dual toroidal dipole resonances.
• Electric multipole interactions significantly influence the energy levels of TD resonances.
• These dual TD metamaterials hold promise for functional terahertz devices.