Highly Efficient Focusing of Terahertz Waves with an Ultrathin Superoscillatory Metalens: Experimental Demonstration

Advanced Photonics Research

Santiago Legaria¹  Miguel Beruete¹  Jorge Teniente¹  Sergei Kuznetsov²  Victor Pacheco-Peña³ 

[1] Antennas Group Public University of Navarra 31006 Pamplona Spain;Rzhanov Institute of Semiconductor Physics SB RAS Novosibirsk Branch “TDIAM”, Lavrentiev Avenue 2/1 Novosibirsk 630090 Russian Federation;School of Mathematics, Statistics and Physics Newcastle University Newcastle upon Tyne NE1 7RU UK;

关键词: metasurfaces;    subwavelength focusing;    superoscillations;    superoscillatory lens;    terahertz;   

DOI  :  10.1002/adpr.202000165

来源: DOAJ

【 摘 要 】

The performance of an ultrathin (thickness < 0.04λ 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 8.9λ exp away from its output surface with a transversal resolution of 0.52λ 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.

【 授权许可】

Unknown