Reflectionless zero refractive index metasurface in the terahertz waveband

Area of Science:

• Metamaterials and Nanophotonics
• Electromagnetism and Optics
• Terahertz Technology

Background:

• Zero refractive index materials exhibit unique electromagnetic properties, behaving as single points with infinite phase velocity.
• Naturally occurring materials cannot achieve a zero refractive index due to the vanishing requirement for both dielectric and magnetic properties.

Purpose of the Study:

• To demonstrate a functional zero refractive index metasurface.
• To investigate the electromagnetic properties of artificial materials at terahertz frequencies.

Main Methods:

• Fabrication of a metasurface designed to exhibit near-zero refractive index.
• Electromagnetic characterization of the metasurface at 0.505 THz, measuring reflectance, transmittance, relative permittivity, and relative permeability.

Main Results:

• Achieved a zero refractive index metasurface with a refractive index of 0.16 + j0.09.
• Measured low reflectance (0.7%) and high transmittance (97.3%) at 0.505 THz.
• Observed simultaneous near-zero values for both relative permittivity (0.18 - j0.10) and relative permeability (0.004 + j0.16), indicating vanishing dielectric and magnetic properties.

Conclusions:

• The demonstrated metasurface successfully realizes a zero refractive index, a feat not possible with natural materials.
• This artificial material platform offers unprecedented functionalities for terahertz applications.
• Potential applications include 6G wireless communications, advanced imaging, and security systems.