Resonant tunneling diode integrated with metalens for high-directivity terahertz waves

Abstract

Terahertz flat optics based on our originally developed low-reflection metasurface with a high refractive index can offer attractive two-dimensional optical components for the manipulation of terahertz waves. However, it remains to be shown whether a planar collimating metalens made with our original metasurface could be mounted on a resonant tunneling diode with a short distance. Here, we demonstrate that a collimating metalens with a distance of 1.0 mm from the RTD enhances the directivity to 3.0 times at 0.312 THz. The proposed metalens would be integrated with various terahertz continuous-wave sources for emerging industry such as 6 G (beyond 5 G) communications.

Analysis of terahertz double dielectric structure patch antenna using nitride semiconductors

“…Terahertz waves are electromagnetic waves in a frequency band of 0.1 to 10 THz that combine properties of both radio waves and light. As regards radio wave properties, terahertz waves feature high resolution due to the short wavelength of 30 µm to 3 mm, while having a waveband wider than that of millimeter waves used in 5G high‐speed wireless communications; thus, there use for post‐5G/6G communications is under consideration 1 . On the other hand, regarding light properties, terahertz waves feature high straightness, high permeability, resistance to scattering, while molecular‐specific absorption spectra can be observed; these properties encourage applied research in imaging and spectroscopy 2,3 .…”

Circularly polarized plane terahertz waves radiated from a resonant tunneling diode integrated with a collimating metalens and quarter-wave plate

“…Flat optics based on metasurfaces [28][29][30] can offer 2D optically thin components as alternatives to 3D optical components employing naturally occurring materials. Lowreflection metasurfaces with a high refractive index have been applied to gradient-refractive-index collimating metalenses 31,32) that can convert wide-angle radiation waves from a terahertz CW source to collimated plane waves with high directivity. The low-reflection metasurface with a high refractive index has also been applied to a refractive plate.…”

“…31,32) The parameters adopted here are d 1 = 23 μm, t 1 = 0.5 μm, and f = 3.0 mm. The collimating metalens with a distance f of 3.0 mm is designed and fabricated to effectively verify the performance of the two-layer component, while the work in 31,32) has a distance f of 10 and 1.0 mm. The radius r of the designed collimating metalens is 1.59 mm.…”

Broadband, large-numerical-aperture and high-efficiency microwave metalens by using a double-layer transmissive metasurface

“…ecently, metalens has become a frontier and hot topic in the field of metasurfaces and/or metamaterials. [1][2][3][4][5][6][7][8][9][10][11] Based on the efficient light manipulation on the ultrathin and flat interface with a series of phase gradient elements, metalenses provide an innovative platform for bending, collimating and focusing an incident wave. The focusing performances of metalens are definitely the core and can also determine its scope for further practical applications.…”