Open AccessAll-dielectric transformation medium mimicking a broadband converging lens
Author(s) -
Tao Liu,
Rui Feng,
Jianjia Yi,
Shah Nawaz Burokur,
Chunxu Mao,
Hailin Zhang,
Douglas H. Werner
Publication year - 2018
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.020331
Subject(s) - optics , lens (geology) , antenna (radio) , physics , beam divergence , transformation optics , angular spectrum method , vortex , microwave , telecommunications , beam diameter , metamaterial , diffraction , computer science , quantum mechanics , laser , laser beams , thermodynamics
Radio waves carrying orbital angular momentum (OAM) may potentially increase spectrum efficiency and channel capacity based on their extra rotational degree of freedom. However, due to their divergence characteristics, vortex waves are not suitable to transmit over a long distance in the radio frequency (RF) and microwave domains. In this paper, a transformation optics (TO) based all-dielectric converging lens is proposed. The beam divergence angle of the vortex wave passing through the lens can be decreased from 25° to 9°. The transformed material parameters of the converging lens are determined by solving Laplace's equation subject to specific boundary conditions. Far-field antenna radiation patterns as well as near-field helical phase and electric field amplitude distributions obtained from numerical simulations are reported, demonstrating the broadband characteristics of the proposed microwave lens. Moreover, the all-dielectric compact lens design comprised by a graded permittivity profile can be fabricated by additive manufacturing technology, which greatly facilitates the potential development and application of vortex wave based wireless communications.