Spontaneous density grating formation in suspensions of dielectric nanoparticles

Mark Wiggins, Gordon Robb, Brian McNeil, David Jones, Steven Jamison, Dino Jaroszynski

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Experimental evidence for nonlinear optical behaviour due to the spontaneous formation of wavelength-scale density modulations or gratings in suspensions of dielectric particles is presented. A collection of dielectric particles pumped by a coherent radiation field may simultaneously form a density grating on the scale of the radiation wavelength and a coherently backscattered radiation field. The particle density grating is generated as a result of a periodic ponderomotive potential formed by the interference of the pump and backscattered fields. The experiment used a water suspension of latex microspheres (radius ≈ 56nm) pumped by a green CW laser (532nm, power ≤ 5W). A theoretical model of collective scattering of light from dielectric particles has been extended to include the effects of viscous and Brownian forces on the particles. This model predicts a small degree of particle bunching from which coherent backscattering of the pump occurs. The results of the theoretical model compare favourably with the experimental evidence. The relation between the results presented here and the phenomenon of Collective Rayleigh Scattering (CRS) is discussed.
Original languageEnglish
Pages (from-to)997-1006
Number of pages10
JournalJournal of Modern Optics
Volume49
Issue number5-6
DOIs
Publication statusPublished - 15 Apr 2002

Keywords

  • dielectric nanoparticles
  • nonlinear optical behaviour
  • spontaneous density grating formation
  • Collective Rayleigh Scattering

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