Three-dimensional invisibility cloaks functioning at terahertz frequencies

Wei Cao, Fan Zhou, Dachuan Liang, Jianqiang Gu, Jiaguang Han, Cheng Sun, Weili Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Quasi-three-dimensional invisibility cloaks, comprised of either homogeneous or inhomogeneous media, are experimentally demonstrated in the terahertz regime. The inhomogeneous cloak was lithographically fabricated using a scalable Projection Microstereolithography process. The triangular cloaking structure has a total thickness of 4.4 mm, comprised of 220 layers of 20 Î1/4m thickness. The cloak operates at a broad frequency range between 0.3 and 0.6 THz, and is placed over an α-lactose monohydrate absorber with rectangular shape. Characterized using angular-resolved reflection terahertz time-domain spectroscopy, the results indicate that the terahertz invisibility cloak has successfully concealed both the geometrical and spectroscopic signatures of the absorber, making it undetectable to the observer. The homogeneous cloaking device made from birefringent crystalline sapphire features a large concealed volume, low loss, and broad bandwidth. It is capable of hiding objects with a dimension nearly an order of magnitude larger than that of its lithographic counterpart, but without involving complex and time-consuming cleanroom processing. The cloak device was made from two 20-mm-thick high-purity sapphire prisms. The cloaking region has a maximum height 1.75 mm with a volume of approximately 5% of the whole sample. The reflected TM beam from the cloak shows nearly the same profile as that reflected by a flat mirror.

Original languageEnglish (US)
Title of host publicationTerahertz Physics, Devices, and Systems VIII
Subtitle of host publicationAdvanced Applications in Industry and Defense
ISBN (Print)9781628410396
StatePublished - Jan 1 2014
EventTerahertz Physics, Devices, and Systems VIII: Advanced Applications in Industry and Defense - Baltimore, MD, United States
Duration: May 5 2014May 6 2014

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherTerahertz Physics, Devices, and Systems VIII: Advanced Applications in Industry and Defense
Country/TerritoryUnited States
CityBaltimore, MD


  • Invisibility cloaking
  • Metamaterials
  • Terahertz
  • Three-dimensional
  • Transformation optics

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Three-dimensional invisibility cloaks functioning at terahertz frequencies'. Together they form a unique fingerprint.

Cite this