Roadmap for Optical Tweezers published in Journal of Physics: Photonics

Illustration of an optical tweezers holding a particle. (Image by A. Magazzù.)
Roadmap for optical tweezers
Giovanni Volpe, Onofrio M Maragò, Halina Rubinsztein-Dunlop, Giuseppe Pesce, Alexander B Stilgoe, Giorgio Volpe, Georgiy Tkachenko, Viet Giang Truong, Síle Nic Chormaic, Fatemeh Kalantarifard, Parviz Elahi, Mikael Käll, Agnese Callegari, Manuel I Marqués, Antonio A R Neves, Wendel L Moreira, Adriana Fontes, Carlos L Cesar, Rosalba Saija, Abir Saidi, Paul Beck, Jörg S Eismann, Peter Banzer, Thales F D Fernandes, Francesco Pedaci, Warwick P Bowen, Rahul Vaippully, Muruga Lokesh, Basudev Roy, Gregor Thalhammer-Thurner, Monika Ritsch-Marte, Laura Pérez García, Alejandro V Arzola, Isaac Pérez Castillo, Aykut Argun, Till M Muenker, Bart E Vos, Timo Betz, Ilaria Cristiani, Paolo Minzioni, Peter J Reece, Fan Wang, David McGloin, Justus C Ndukaife, Romain Quidant, Reece P Roberts, Cyril Laplane, Thomas Volz, Reuven Gordon, Dag Hanstorp, Javier Tello Marmolejo, Graham D Bruce, Kishan Dholakia, Tongcang Li, Oto Brzobohatý, Stephen H Simpson, Pavel Zemánek, Felix Ritort, Yael Roichman, Valeriia Bobkova, Raphael Wittkowski, Cornelia Denz, G V Pavan Kumar, Antonino Foti, Maria Grazia Donato, Pietro G Gucciardi, Lucia Gardini, Giulio Bianchi, Anatolii V Kashchuk, Marco Capitanio, Lynn Paterson, Philip H Jones, Kirstine Berg-Sørensen, Younes F Barooji, Lene B Oddershede, Pegah Pouladian, Daryl Preece, Caroline Beck Adiels, Anna Chiara De Luca, Alessandro Magazzù, David Bronte Ciriza, Maria Antonia Iatì, Grover A Swartzlander Jr
Journal of Physics: Photonics 2(2), 022501 (2023)
arXiv: 2206.13789
doi: 110.1088/2515-7647/acb57b

Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration.

Fractal Plasmonics published in Opt. Express

Fractal plasmonics: Subdiffraction focusing and broadband spectral response by a Sierpisky nanocarpet

Fractal plasmonics: Subdiffraction focusing and broadband spectral response by a Sierpisky nanocarpet
Giorgio Volpe, Giovanni Volpe & Romain Quidant
Optics Express 19(4), 3612—3618 (2011)
DOI: 10.1364/OE.19.003612

Plasmonic nanostructures offer a great potential to enhance light-matter interaction at the nanometer scale. The response upon illumination at a given wavelength and polarization is governed by the characteristic lengths associated to the shape and size of the nanostructure. Here, we propose the use of engineered fractal plasmonic structures to extend the degrees of freedom and the parameters available for their design. In particular, we focus on a paradigmatic fractal geometry, namely the Sierpinski carpet. We explore the possibility of using it to achieve a controlled broadband spectral response by controlling the degree of its fractal complexity. Furthermore, we investigate some other arising properties, such as subdiffraction limited focusing and its potential use for optical trapping of nano-objects. An attractive advantage of the focusing over more standard geometries, such as gap antennas, is that it occurs away from the metal surface (≈ 80nm) at the center of the nanostructure, leaving an open space accessible to objects for enhanced light-matter interaction.

Surface Plasmon Optical Tweezers published in Phys. Rev. Lett.

Surface plasmon optical tweezers: Tunable optical manipulation in the femtonewton range

Surface plasmon optical tweezers: Tunable optical manipulation in the femtonewton range
Maurizio Righini, Giovanni Volpe, Christian Girard, Dmitri Petrov & Romain Quidant
Physical Review Letters 100(18), 186804 (2008)
DOI: 10.1103/PhysRevLett.100.186804

We present a quantitative analysis of 2D surface plasmon based optical tweezers able to trap microcolloids at a patterned metal surface under low laser intensity. Photonic force microscopy is used to assess the properties of surface plasmon traps, such as confinement and stiffness, revealing stable trapping with forces in the range of a few tens of femtonewtons. We also investigate the specificities of surface plasmon tweezers with respect to conventional 3D tweezers responsible for their selectivity to the trapped specimen’s size. The accurate engineering of the trapping properties through the adjustment of the illumination parameters opens new perspectives in the realization of future optically driven on-a-chip devices.

Surface Plasmon Radiation Forces published in Phys. Rev. Lett.

Surface plasmon radiation forces

Surface plasmon radiation forces
Giovanni Volpe, Romain Quidant, Gonçal Badenes & Dmitri Petrov
Physical Review Letters 96(23), 238101 (2006)
DOI: 10.1103/PhysRevLett.96.238101

We report the first experimental observation of momentum transfer from a surface plasmon to a single dielectric sphere. Using a photonic force microscope, we measure the plasmon radiation forces on different polystyrene beads as a function of their distance from the metal surface. We show that the force magnitude at resonance is strongly enhanced compared to a nonresonant illumination. Measurements performed as a function of the probe particle size indicate that optical manipulation by plasmon fields has a strong potential for optical sorting.