Optical trapping

Since the first observation by A. Ashkin and co-workers in 1986, the single-beam laser trap or ‘Optical Tweezers’ has become a commonly used tool in both the physical and life sciences for the manipulation of micron-sized objects and as a force transducer in the sub-piconewton range. In our lab we use single-beam, dynamic, steerable or holographic optical tweezers to trap spherical and non-spherical particles at the nanoscale. We concentrate our efforts to trap and manipulate nanoparticles dispersed in liquids such as carbon nanotubes, graphene, layered materials, polymer nanofibers, silicon nanowires, plasmonic nanostructures (individual metal particles and aggregates). We have also used optical tweezers to study the chiral optomechanics of chiral microparticles based on cholesteric liquid crystals.

A great amount of work is also devoted to the theoretical modeling of optical trapping of non-spherical particles using light scattering theory in the T-matrix formalism.

Textbook: Jones, P. H., Maragò, O. M., Volpe, G. Optical Tweezers: Principles and Applications, Cambridge University Press, Cambridge, UK (2015).

Selected references:

  1. Donato, et al. Optical trapping and optical force positioning of two-dimensional materials. Nanoscale 10, 1245-1255 (2018).
  2. Simpson, et al. Optical binding of nanowires. Nano Letters 17, 3485-3492 (2017).
  3. Spadaro, et al. Optical Trapping of Plasmonic Mesocapsules: Enhanced Optical Forces and SERS. The Journal of Physical Chemistry C 121, 691-700 (2017).
  4. Donato, et al. Light-induced rotations of chiral birefringent microparticles in optical tweezers. Scientific Reports 6 (2016).
  5. Fazio, et al. SERS detection of Biomolecules at Physiological pH via aggregation of Gold Nanorods mediated by Optical Forces and Plasmonic Heating. Scientific Reports 6 (2016).
  6. Irrera, et al. Photonic torque microscopy of the nonconservative force field for optically trapped silicon nanowires. Nano Letters 16, 4181-4188 (2016).
  7. Donato, et al. “Polarization-dependent optomechanics mediated by chiral microresonators. Nature Communications 5, 3656 (2014).
  8. Maragò, et al., Optical trapping and manipulation of nanostructures. Nature Nanotechnology 8, 807 (2013).
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