Optical Trapping

A strongly focused beam of light can be used to trap and move objects ranging in size from tens of nanometers to tens of micrometers. These optical tweezers have become a widely-used tool in biology, physical chemistry, and fundamental physics, and the invention was awarded the 2018 Nobel Prize in Physics. The group have worked in optical trapping for over two decades, and some of our recent research directions are highlighted below.

Optical Binding

Optically mediated interactions between trapped objects can cause attractive and repulsive forces and dramatically influence the way they assemble and organize themselves. This offers routes for self-assembly of crystalline “optical matter”.

  • TRANSVERSE OPTICAL BINDING FOR A DUAL DIPOLAR DIELECTRIC NANOPARTICLE DIMER
    X.-Y. Duan, G. D. Bruce, K. Dholakia, Z.-G. Wang, F. Li, Y.-P. Yang, arXiv:2008.07243
  • OPTICAL BINDING OF TWO COOLED MICRO-GYROSCOPES LEVITATED IN VACUUM
    Y. Arita, E. M. Wright and K. Dholakia, Optica 5, 910 (2018)
  • ROTATION OF TWO TRAPPED MICROPARTICLES IN VACUUM: OBSERVATION OF OPTICALLY MEDIATED PARAMETRIC RESONANCES
    Y. Arita, M. Mazilu, T. Vettenburg, E. M. Wright and K. Dholakia, Opt. Lett. 40, 4751 (2015)
  • COLLOQUIUM: GRIPPED BY LIGHT: OPTICAL BINDING
    K. Dholakia and P. Zemanek, Rev. Mod. Phys. 82, 1767 (2010)

Optical Rotation

Anisotropic optically trapped particles can be made to spin by using circularly-polarised light. When this rotation takes place in vacuum, the particle can rotate about its own axis several million times per second, creating a gyroscopic effect which stabilises the particle’s motion and cools the translational energy to 40K. The orbital angular momentum of light can also be used to impart rotational motion on the trapped object. These rotational effects in levitated optomechanics may be of interest in guided matter-wave interferometry of massive particles, and in the hunt for quantum friction.

  • COHERENT OSCILLATIONS OF A LEVITATED BIREFRINGENT MICROSPHERE IN VACUUM DRIVEN BY NONCONSERVATIVE ROTATION-TRANSLATION COUPLING
    Y. Arita, S. H. Simpson, P. Zemánek, and K. Dholakia, Sci. Adv. 6, eaaz9858 (2020)
  • DYNAMICS OF A LEVITATED MICROPARTICLE IN VACUUM TRAPPED BY A PERFECT VORTEX BEAM: THREE DIMENSIONAL MOTION AROUND A COMPLEX OPTICAL POTENTIAL
    Y. Arita, M. Chen, E. M. Wright and K. Dholakia, J. Opt. Soc. Am. B 34, C14 (2017)
  • ORBITAL-ANGULAR-MOMENTUM TRANSFER TO OPTICALLY LEVITATED MICROPARTICLES IN VACUUM
    M. Mazilu, Y. Arita, T. Vettenburg, J. M. Auñón Garcia, E. M. Wright and K. Dholakia, Phys. Rev. A 94, 053821 (2016)
  • LASER-INDUCED ROTATION AND COOLING OF A TRAPPED MICROGYROSCOPE IN VACUUM
    Y. Arita, M. Mazilu and K. Dholakia, Nat Commun. 4, 2374 (2013)

Unconventional Trapping Materials

An under-explored area of optical trapping is the influence of the material properties of the trapped particle. A careful choice of the properties of the particle in the light can allow significant flexibility in tailoring the optical forces torques, and even the temperature of the particles.

  • THE TEMPERATURE OF AN OPTICALLY TRAPPED, ROTATING MICROPARTICLE
    P. Rodriguez-Sevilla, Y. Arita, X. Liu, D. Jaque and K. Dholakia, ACS Photonics 5, 3772 (2018)
  • OPTICAL TRAPPING OF ULTRASMOOTH GOLD NANOPARTICLES IN LIQUID AND AIR
    Y. Arita, G. Tkachenko, N. McReynolds, N. Marro, W. Edwards, E. R. Kay and K. Dholakia, APL Photonics 3, 070801 (2018)
  • ROTATIONAL DYNAMICS AND HEATING OF TRAPPED NANOVATERITE PARTICLES
    Y. Arita, J. Richards, M. Mazilu, G. Spalding, S. E. Skelton Spesyvtseva, D. Craig and K. Dholakia, ACS Nano 10, 11505  (2016)
  • TRAPPING IN A MATERIAL WORLD
    S. E. Skelton Spesyvtseva and K. Dholakia, ACS Photonics 3, 719 (2016)

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