Analysis of nanoparticles using photonic nanojet

Xu Li*, Zhigang Chen, Michael P. Siegel, Allen Taflove, Vadim Backman

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

5 Scopus citations


A photonic nanojet is a local field enhancement generated in the vicinity of a properly chosen microsphere or microcylinder illuminated by a collimated light beam. These photonic nanojets have waists smaller than the diffraction limit and propagate over several optical wavelengths without significant diffraction. We investigate the properties of photonic nanojets using rigorous solutions of Maxwell's equations. A remarkable property we have found is that they can significantly enhance the backscattering of light by nanometer-scale particles (as small as -1 nm) located within the jets. The enhancement factor for the backscattering intensity can be as high as five to six orders of magnitude. As a result, the observed intensity of the backscattered light from the dielectric microsphere can be substantially altered due to the presence of a nanoparticle within the light jet. Furthermore, the intensity and angular distribution of the backscattered signal is extremely sensitive to the size of the nanoparticle, which may enable differentiating particles with accuracy up to 1 nm. These properties of photonic nanojets make them an ideal tool for detecting, differentiating and sorting nanoparticles, which is of immense necessity for the field of nano-biotechnology. For example, they could yield potential novel ultramicroscopy techniques using visible light for detecting proteins, viral particles, and even single molecules; and monitoring molecular synthesis and aggregation processes of importance in many areas of biology, chemistry, material sciences, and tissue engineering.

Original languageEnglish (US)
Article number04
Pages (from-to)14-22
Number of pages9
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
StatePublished - Aug 16 2005
EventNanobiophotonics and Biomedical Applications II - San Jose, CA, United States
Duration: Jan 24 2005Jan 27 2005


  • Diffraction limit
  • Light scattering
  • Near-field scanning optical microscopy
  • Ultramicroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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