Terahertz spoof surface plasmon polariton gradient index lens

• Published in: Results in physics 2023-04, Vol.47, p.106332, Article 106332
• Main Authors: Gu, Shenghao, Yuan, Xinyao, Liu, Lei, Sun, Mingming, Zhang, Ying, Xu, Quan, Han, Jiaguang
• Format: Article
• Language: English
• Subjects: Gradient index lens; Spoof surface plasmon polaritons; Terahertz devices
• ISSN: 2211-3797; 2211-3797
• DOI: 10.1016/j.rinp.2023.106332

•The subwavelength focusing function of lenses is analyzed in more detail.•A series of GRIN lenses components based on periodic pillars were designed and studied experimentally.•By using scanning nera-field THz microscopy, the images of electric field distribution for all structures were displayed. Plasmonics takes advantage of surface plasmon polaritons (SPPs), which have the characteristics of strong subwavelength field confinement and enhancement. Plasmonic devices that confine light in regions with dimensions that are smaller than the wavelength have important application prospects in on-chip integrated circuits. Nonetheless, at terahertz frequencies, the weak confinement of SPPs and immature near-field technology hinder the development of related devices. Here, a highly confined SPP mode (spoof SPP) is implemented by structuring metal surfaces. Gradient index lenses with variable indices are constructed by fine-tuning the size of the pillars, and the characteristics of several different lenses are examined and explored by scanning near-field terahertz microscopy. Thus, terahertz waves are regulated and more possibilities are provided for further miniaturization and compactness of THz devices.