Open AccessHighly Efficient Focusing of Terahertz Waves with an Ultrathin Superoscillatory Metalens: Experimental Demonstration
Author(s) -
Legaria Santiago,
Teniente Jorge,
Kuznetsov Sergei,
Pacheco-Peña Victor,
Beruete Miguel
Publication year - 2021
Publication title -
advanced photonics research
Language(s) - English
Resource type - Journals
ISSN - 2699-9293
DOI - 10.1002/adpr.202000165
Subject(s) - terahertz radiation , optics , diffraction , opacity , materials science , resolution (logic) , bandwidth (computing) , optoelectronics , lens (geology) , physics , telecommunications , computer science , artificial intelligence
The performance of an ultrathin (thickness < 0.04 λ 0 ) metasurface superoscillatory lens (metaSOL) is experimentally demonstrated in the terahertz (THz) range. The metaSOL is designed using two different hexagonal unit cells to improve the efficiency and properties of the conventional transparent–opaque zoning approach. The focusing metastructure produces, at a frequency f exp = 295 GHz, a sharp focal spot 8.9 λ exp away from its output surface with a transversal resolution of 0.52 λ exp (≈25% below the resolution limit imposed by diffraction), a power enhancement of 18.2 dB, and very low side lobe level (−13 dB). Resolution below the diffraction limit is demonstrated in a broad fractional operation bandwidth of 18%. The focusing capabilities of the proposed metaSOL show its potential use in a range of applications such as THz imaging, microscopy, and communications.