Optical analysis of nanoparticles via enhanced backscattering facilitated by 3-D photonic nanojets

Xu Li*, Zhigang Chen, Allen Taflove, Vadim Backman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

254 Scopus citations


We report the phenomenon of ultra-enhanced backscattering of visible light by nanoparticles facilitated by the 3-D photonic nanojet - a sub-diffraction light beam appearing at the shadow side of a plane-wave-illuminated dielectric microsphere. Our rigorous numerical simulations show that backscattering intensity of nanoparticles can be enhanced up to eight orders of magnitude when locating in the nanojet. As a result, the enhanced backscattering from a nanoparticle with diameter on the order of 10 nm is well above the background signal generated by the dielectric microsphere itself. We also report that nanojet-enhanced backscattering is extremely sensitive to the size of the nanoparticle, permitting in principle resolving sub-nanometer size differences using visible light. Finally, we show how the position of a nanoparticle could be determined with subdiffractional accuracy by recording the angular distribution of the backscattered light. These properties of photonic nanojets promise to make this phenomenon a useful tool for optically detecting, differentiating, and sorting nanoparticles.

Original languageEnglish (US)
Pages (from-to)526-533
Number of pages8
JournalOptics Express
Issue number2
StatePublished - Jan 2005

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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