Highly Efficient Focusing of Terahertz Waves with an Ultrathin Superoscillatory Metalens: Experimental Demonstration. Issue 9 (26th July 2021)

• Record Type: Journal Article
• Authors: Legaria, Santiago; Teniente, Jorge; Kuznetsov, Sergei; Pacheco-Peña, Victor; Beruete, Miguel
• Is Part Of: Advanced photonics research. Volume 2:Issue 9(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-07-26
• Subjects: metasurfaces -- subwavelength focusing -- superoscillations -- superoscillatory lens -- terahertz; Photonics -- Periodicals; 621.36505
• DOI: 10.1002/adpr.202000165
• Languages: English
• ISSNs: 2699-9293

Abstract

Abstract : 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. Abstract : An ultrathin metasurface‐based superoscillatory lens is designed and experimentally demonstrated working at Terahertz (THz). The spatial resolution of the resulting focus (at distance z = 9 mm) is improved by 25% above the resolution limit while achieving very low side lobes, an enhancement of 18.2 dB, and high yield. This lens may open new avenues for high‐resolution THz lenses.