Parametric excitation of optically trapped aerosols

R. Di Leonardo*, G. Ruocco, J. Leach, M. J. Padgett, A. J. Wright, J. M. Girkin, D. R. Burnham, D. McGloin

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingPublished conference contribution


The Brownian dynamics of an optically trapped water droplet is investigated across the transition from over to under-damped oscillations. The spectrum of position fluctuations evolves from a Lorentzian shape typical of over-damped systems (beads in liquid solvents), to a damped harmonic oscillator spectrum showing a resonance peak. In this later under-damped regime, we excite parametric resonance by periodically modulating the trapping power at twice the resonant frequency. We also derive from Langevin dynamics an explicit numerical recipe for the fast computation of the power spectra of a Brownian parametric oscillator. The obtained numerical predictions are in excellent agreement with the experimental data.

Original languageEnglish
Title of host publicationProceedings SPIE: Optical Trapping and Optical Micromanipulation IV
Publication statusPublished - 2007
EventNanoScience + Engineering: Society of Photo-Optical Instrumentation Engineers (SPIE) - San Diego, CA, United States
Duration: 26 Aug 200729 Aug 2007


ConferenceNanoScience + Engineering
Country/TerritoryUnited States
CitySan Diego, CA


  • Brownian motion
  • Optical tweezers
  • Parametric resonance


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