title: Terahertz epsilon-near-zero graded-index lens.
abstract: An epsilon-near-zero graded-index converging lens with planar faces is proposed and analyzed. Each perfectly-electric conducting (PEC) waveguide comprising the lens operates slightly above its cut-off frequency and has the same length but different cross-sectional dimensions. This allows controlling individually the propagation constant and the normalized characteristic impedance of each waveguide for the desired phase front at the lens output while Fresnel reflection losses are minimized. A complete theoretical analysis based on the waveguide theory and Fermat's principle is provided. This is complemented with numerical simulation results of two-dimensional and three-dimensional lenses, made of PEC and aluminum, respectively, and working in the terahertz regime, which show good agreement with the analytical work.
authors.affiliation: TERALAB (MmW – THz – IR & Plasmonics Laboratory), Universidad Pública de Navarra, Pamplona 31006, Spain. victor.torres@unavarra.es
authors.forename: Víctor
authors.initials: V
authors.lastname: Torres
authors.forename: Víctor
authors.initials: V
authors.lastname: Pacheco-Peña
authors.forename: Pablo
authors.initials: P
authors.lastname: Rodríguez-Ulibarri
authors.forename: Miguel
authors.initials: M
authors.lastname: Navarro-Cía
authors.forename: Miguel
authors.initials: M
authors.lastname: Beruete
authors.forename: Mario
authors.initials: M
authors.lastname: Sorolla
authors.forename: Nader
authors.initials: N
authors.lastname: Engheta
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007909:Lenses; D055053:Terahertz Radiation