Cylindrical Fresnel lenses based on carbon nanotube forests

Research output: Contribution to journalArticlepeer-review


  • Haider Butt
  • Ranjith Rajesekharan
  • Qing Dai
  • Sohab Sarfraz
  • R. Vasant Kumar
  • Gehan A J Amaratunga
  • Timothy D. Wilkinson

Colleges, School and Institutes

External organisations

  • University of Cambridge
  • Department of Chemical Engineering
  • University of Melbourne
  • Sri Lanka Institute of Nanotechnology (SLINTEC)


The forests of carbon nanotubes have been termed as the darkest man-made materials. Such materials exhibit near-perfect optical absorption (reflectance∼0.045%) due to low reflectance and nanoscale surface roughness. We have demonstrated the utilization of these perfectly absorbing forests to produce binary amplitude cylindrical Fresnel lenses. The opaque Fresnel zones are defined by the dark nanotube forests and these lenses display efficient focusing performance at optical wavelengths. Lensing performance was analyzed both computationally and experimentally with good agreement. Such nanostructure based lenses have many potential applications in devices like photovoltaic solar cells.


Original languageEnglish
Article number243116
JournalApplied Physics Letters
Issue number24
Publication statusPublished - 10 Dec 2012

ASJC Scopus subject areas