addition to an immersive program of oral presentations, our poster sessions have a tradition of ensuring an excellent level of interaction and feedback. The proceedings of the conference contain a large collection of relevant papers, making a valuable contribution to the field. Early career researchers are especially encouraged and highlighted.

Joint sessions will be planned with the "Emerging Topics in Artificial Intelligence" conference.

Papers are solicited on (but not restricted to) the following areas: ;
In progress – view active session
Conference 12198

Optical Trapping and Optical Micromanipulation XIX

21 - 24 August 2022
View Session ∨
  • 1: Studies of Dynamical Biophysical Systems
  • 2: Biophotonic Lab-on-a-Chip & Hybrid Systems I
  • 3: Biophotonic Lab-on-a-Chip & Hybrid Systems II
  • 4: Biophotonic Lab-on-a-Chip & Hybrid Systems III
  • 5: Photonic Devices for Optically Induced Forces
  • 6: Systems with Broken Symmetry, Including Optical Angular Momentum
  • 7: Shaping the Flow of Information, Energy, and Momentum
  • 8: Precision Measurement Including Testing Fundamental Physics I
  • 9: Optical Manipulation of Matter Through Gaseous Media
  • 10: Precision Measurement Including Testing Fundamental Physics II
  • 11: Near-Field Micromanipulation, Plasmonic, and Nanoparticle Trapping
  • 12: Statistical Mechanics of Small Systems
  • 13: Extensions of the OTOM Toolkit
  • Poster Session
  • Sunday Evening Plenary
  • Nanoscience + Engineering Plenary


  • Submissions accepted through 5-July

Call for Papers Flyer
Session 1: Studies of Dynamical Biophysical Systems
Session Chair: Daryl C. Preece, Beckman Laser Institute and Medical Clinic (United States)
Author(s): Michael Himmelsbach, Jordan Zesch, Ernst-Ludwig Florin, The Univ. of Texas at Austin (United States)
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The mechanics of filament networks depend on both the individual filament properties and the network architecture. Despite the importance of filament networks in biology, there exists no technique which can precisely localize filaments and cross-links in three dimensions and simultaneously resolve their dynamics. Thermal noise imaging is a three-dimensional scanning probe technique that utilizes the confined thermal motion of an optically trapped nanoparticle to noninvasively probe the sample. Here, we apply the technique to a stably crosslinked network of microtubules. The filament axes are localized with a precision of 4nm. Analysis also reveals fluctuations of individual filaments and properties of cross-links.
Author(s): Dana Reinemann, The Univ. of Mississippi (United States)
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A challenge within the motor biophysics field is reconstituting a motor-filament environment that reflects physiological function. Many optical trapping studies of motor proteins employ a reductionist geometry of a single motor interacting with a single filament. These conformations do not accurately represent the structural architecture in which motors with crosslinking ability, such as myosins or mitotic kinesins, function. Thus, we engineered customizable “nanocells” of reconstituted protein assemblies to probe hierarchical cytoskeletal mechanics with high resolution using optical tweezers.
Author(s): Nicole Wakida, Vincent Nguyen, Michael W. Berns, Univ. of California (United States)
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The use of laser nanosurgery to induce photolysis has proven to be an indispensable tool for in vitro studies of astrocytes. Here, we utilize laser nanosurgery to initiate damage within single astrocytes in an vitro traumatic brain injury model. Changes in cytoplasmic ATP levels were observed throughout the astrocyte network following the targeted lysis of a single cell. In response to the death of a neighboring cell, a transient drop in cytoplasmic ATP levels was observed. This combined method of optical technologies should prove valuable in understanding astrocytes’ role in detection of nervous tissue damage.
Session 2: Biophotonic Lab-on-a-Chip & Hybrid Systems I
Session Chair: Halina Rubinsztein-Dunlop, The Univ. of Queensland (Australia)
Author(s): Cuifeng Ying, Arman Yousefi, Ze Zheng, Lei Xu, Mohsen Rahmani, Nottingham Trent Univ. (United Kingdom)
Author(s): Reuven Gordon, Univ. of Victoria (Canada)
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This presentation will focus on enhancing the usability of double-nanohole (DNH) optical tweezers in protein analysis applications. We will compare the technique with existing label-free and tether-free methods, showing that the DNH has an order of magnitude lower limit of detection and higher sensitivity. We will also present advances for low-cost and high-througput analysis, with applications to drug discovery, drug validation and biologics. We will also discuss applications to the analysis of perovskite quantum dots.
Author(s): Elisa Ortiz-Rivero, Univ. Autónoma de Madrid (Spain)
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Precise and non-invasive control over single particles is key for a range of physical and bio-medical applications, such as microfluidics and biophysics. The analysis of the rotation dynamics of an optically trapped dielectric microparticle is presented as a novel tool to characterize the properties of a liquid medium at the microscale (temperature, viscosity and bio-objects). In this work, single dielectric β-NaYF4:Ln3+ microparticles are used as optical sensors and the analysis of its damped rotational dynamics allowed not only the controlled and remote manipulation of the sensor, but also an improved characterization of the medium and fast recording of its content.
Author(s): Josef A. Käs, Enrico Warmt, Univ. Leipzig (Germany)
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Cell contractility is mainly imagined as a force dipole-like interaction based on actin stress fibers that pull on cellular adhesionsites. Here, we present a different type of contractility based on isotropic contractions within the actomyosin cortex. Measuring mechanosensitive cortical contractility of suspended cells among various cell lines allowed us to exclude effects caused by stressfibers. We found that epithelial cells display a higher cortical tension than mesenchymal cells, directly contrasting to stressfiber-mediated contractility. These two types of contractility can even be used to distinguish epithelial from mesenchymal cells.These findings from a single cell level correlate to the rearrangement effects of actomyosin cortices within cells assembled in multicellular aggregates. Epithelial cells form a collective contractile actin cortex surrounding multicellular aggregates and further generate a high surface tension reminiscent of tissue boundaries. Hence, we suggest this intercellular structure as tobe crucial for epithelial tissue integrity. In contrast, mesenchymal cells do not form collective actomyosin cortices reducing multicellular cohesion and enabling cell escape from the aggregates.
Author(s): Murat Serhatlioglu, Emil A. Jensen, Maria Niora, Technical Univ. of Denmark (Denmark); Anne T. Hansen, Rigshospitalet (Denmark); Christian Friberg Nielsen, Univ. of Copenhagen (Denmark); Michelle M. Theresia Jansman, Leticia Hosta-Rigau, Ctr. for Nanomedicine and Theranostics, Technical Univ. of Denmark (Denmark); Morten H. Dziegiel, Rigshospitalet (Denmark); Kirstine Berg-Sørensen, Technical Univ. of Denmark (Denmark); Ian D. Hickson, Univ. of Copenhagen (Denmark); Anders Kristensen, Technical Univ. of Denmark (Denmark)
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Flow cytometry (FC) is an essential technique to study the physical and chemical properties of synthetic or biological particles. In this study, we developed a portable, optical fiber-based portable viscoelastic FC device, supporting stable viscoelastic focusing for rigid/elastic and spherical/non-spherical particles within a size range of 2-30 µm using fused silica microcapillary channels. Forward scatter, side scatter, and fluorescent emitted light signals can be collected and analyzed in a real-time GUI environment. This portable FC platform fits onto any inverted microscope stage enabling real-time microscopy imaging of the particles of interest using a high-speed camera.
Session 3: Biophotonic Lab-on-a-Chip & Hybrid Systems II
Session Chair: Kishan Dholakia, Univ. of St. Andrews (United Kingdom)
Author(s): Mia Kvåle Løvmo, Benedikt Pressl, Gregor Thalhammer, Monika Ritsch-Marte, Medizinische Univ. Innsbruck (Austria)
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Combining optical tweezers with acoustic trapping in one platform allows us to trap and manipulate sub-millimeter sized biological samples in suspension in a contact-less and flexible manner. The acoustic radiation forces levitate and trap the sample and steerable holographic optical tweezers give us an additional means of manipulation. We have implemented 3D acoustic trapping on a microfluidic chip, with three independent MHz transducers in three orthogonal directions; two side-transducers and one transparent top-transducer facilitating optical access for optical trapping and imaging. We can reorient the samples, or induce sustained rotations to gain access to multiple viewing angles of the object.
Author(s): Jiawei Sun, Nektarios Koukourakis, Jürgen W. Czarske, TU Dresden (Germany)
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We demonstrate a multi-core fiber (MCF)-based optical trap that enables dynamically controlled rotation of cancer cells around all 3D axes for optical diffraction tomography with high spatiotemporal resolution. We introduce a novel deep neural network to accelerate the tailored hologram and enable the generation of complex light fields near the video rate in the high-fidelity capture region. The flexibility of fiber optic manipulation of multi-axis cell rotations opens up new applications for 3D refractive index reconstruction. Deep neural networks bring the MCF-based optical manipulation system to the next level of freedom and open new perspectives for non-contact cellular studies.
Author(s): Declan Armstrong, Halina Rubinsztein-Dunlop, Alexander B. Stilgoe, The Univ. of Queensland (Australia)
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Nanofabrication using two-photon-photopolymerision (2PP) can be used to create complex 3D structures with sub-diffraction-limited resolution for studying a range of microscopic systems. In this work we discuss how the addition of a spatial light modulator (SLM) can optimise the printing process through in-situ aberration correction and wavefront engineering. We show how digital holograms are used to control and fabricate complex patterns using various Gerchberg-Saxton algorithms. We demonstrate the necessity for aberration correction when printing using many independently controlled foci and fabricate devices that are used to study complex biological systems.
Author(s): Tatiana Avsievich, Alexander Bykov, Univ. of Oulu (Finland); Anton Popov, Andrei Kabashin, Aix-Marseille Univ. (France); Igor V. Meglinski, Aston Univ. (United Kingdom)
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In the framework of novel medical paradigm the red blood cells (RBC) have a great potential to be used as drug delivery carriers. This approach is required an ultimate understanding of the peculiarities of mutual interaction of RBC influenced by nano-materials composed the drugs. The Optical Tweezers (OT) is the cutting-edge optical technology and widely used to explore mechanisms of cells interaction with the ability to trap non-invasively, manipulate and displace living cells with a notably high accuracy. In the current study, the mutual interaction of RBC with laser-synthesized plasmonic nanoparticles (NP) is investigated.
Author(s): Nicolas R. Perez, Beckman Laser Institute and Medical Clinic (United States), Univ. of California, Irvine (United States); Anna S. Bezryadina, California State Univ., Northridge (United States); Daryl Preece, Beckman Laser Institute and Medical Clinic (United States), Univ. of California, Irvine (United States)
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The conservation orbital angular momentum and polarization for beams propagating through scattering bio-soft matter enables multiplexed signaling. By utilizing nonlinear optical effects in the scattering bio-soft-matter, we investigate the conservation of polarization and OAM through self-trapping and pump/probe coupled waveguides of light in sheep red blood cell suspensions at 532 nm and 780nm wavelengths. This study provides a basis for further exploration into optical signaling in soft matter systems.
Session 4: Biophotonic Lab-on-a-Chip & Hybrid Systems III
Session Chair: Reuven Gordon, Univ. of Victoria (Canada)
Author(s): Elyas Nasimdoust, Ramin Jamali, Faeze Amarloo, Institute for Advanced Studies in Basic Sciences (Iran, Islamic Republic of); Sabareesh K. P. Velu, Rathinam College of Arts and Science (India); Ali-Reza Moradi, Institute for Advanced Studies in Basic Sciences (Iran, Islamic Republic of)
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The Brownian motion of micro-particles in a fluidic medium can be altered by external light fields. Speckle tweezers (ST), by incorporating randomly distributed light fields can be used to apply detectable limits on the Brownian motion of various micro-particles. Here, we demonstrate that by implementing proper digital masks on a spatial light modulator, it is possible to produce specific ST fields for further controlling the motion of multiple micro-particles. The grain size and grain spatial distribution are kept constant during the experiments. The quasi-2D nature of ST makes it easy to track the trajectories of colloids by digital video microscopy.
Author(s): Donato Conteduca, Univ. of York (United Kingdom); Giusepppe Brunetti, Politecnico di Bari (Italy); Giampaolo Pitruzzello, Univ. of York (United Kingdom); Kishan Dholakia, Univ. of St. Andrews (United Kingdom); Thomas F. Krauss, Univ. of York (United Kingdom); Caterina Ciminelli, Politecnico di Bari (Italy)
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Nanophotonic structures optimise the strength of optical forces, enabling trapping at nanoscale. To improve the impact of nanotweezers in biological studies, it is necessary to move from individual traps to large multiplexed ability. We discuss the state-of-the-art of nanotweezers for multiplexed trapping and focus on our latest results with a dielectric metasurface, supporting strong resonance with thousands of possible trapping sites. We demonstrate near-field enhancement and simulate trapping performance for 100nm particles, verifying the possibility to trap >1000 particles with low total power P<26mW. The multiplexed trapping with dielectric metasurfaces will open up new biological studies on viruses and vesicles.
Author(s): Holger Schmidt, Mohammad Sampad, M. S. Saiduzzaman, Univ. of California, Santa Cruz (United States); Aaron R. Hawkins, Zach Walker, Tanner Wells, Brigham Young Univ. (United States)
Author(s): Markus A. Schmidt, Leibniz-Institut für Photonische Technologien e.V. (Germany)
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Here I will report on nanostructured fibers for optical trapping and tracking of single nano-objects. The first topic addresses the implementation of nanostructures on fibers by 3D nanoprinting. This allows microspheres and bacteria to be trapped with only a single-mode fiber by integrating meta-lenses on the fiber end faces, achieving numerical apertures of up to 0.88. I will also report on the tracking of nanoobjects diffusing in microstructured fibers. I will focus on 3D tracking using evanescent fields and on ensembles of nanoparticles (e.g. bacteriophages) tracked in anti-resonance fibers. I will also present our first results on inactivated SARS-CoV-2.
Session 5: Photonic Devices for Optically Induced Forces
Session Chair: Justus C. Ndukaife, Vanderbilt Univ. (United States)
Author(s): J. Eduardo Lugo, Univ. de Montréal (Canada), Benemérita Univ. Autónoma de Puebla (Mexico); Miller Toledo-Solano, Martha Alicia Palomino-Ovando, Benemérita Univ. Autónoma de Puebla (Mexico); Jocelyn Faubert, Univ. de Montréal (Canada); Hector Cerecedo-Nuñez, Univ. Veracruzana (Mexico)
Author(s): Matthew A. Pelton, Univ. of Maryland, Baltimore County (United States)
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Two common assumptions for simple molecular liquids are that they exhibit a Newtonian response and the no-slip boundary condition at solid-liquid interfaces. By making ultrafast optical measurements of vibrating metal nanoparticles in simple liquids, we have shown that these assumptions can break down on nanometer length scales and on the picosecond time scales that are characteristic of nanoscale motion. Our measurements quantitatively validate a Maxwell model for viscoelasticity in simple, compressible liquids, and provide a measurement of single-nanometer-scale slip lengths at the nanoparticle-liquid interface.
Author(s): Kishan Dholakia, Univ. of St. Andrews (United Kingdom)
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Optical Trapping continues to make enormous impact across the sciences. This talk will describe how novel nanostructured materials can assist in trapping performance. This includes near field trapping and the use of metasurfaces. Separately the talk will discuss the use of novel materials for trapped particles to enhance performance for trapping in liquid and vacuum.
Author(s): Simon Hanna, Michael O'Donnell, Univ. of Bristol (United Kingdom)
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The use of a patterned surface to create an optical conveyor for spherical, and near spherical particles is explored. Using a surface constructed of a repeating micron-sized motif, we simulate the effects of moving a particle in the near-field region above the surface, as well as exploring optical force changes in the axis perpendicular to the surface resulting from changes in size of the particles, and the choice of incident wavelength.
Author(s): Tongcang Li, Purdue Univ. (United States)
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An optically levitated nanoparticle in a vacuum is excellent for precision measurements. We have optically levitated silica nanodumbbells in a vacuum and driven them to rotate beyond 5 GHz. With an optically levitated nanorotor, we demonstrated a torque sensor with a record-high sensitivity [Nature Nanotechnology, 15, 89 (2020)]. Recently, we designed and fabricated an ultrathin metalens with a high numerical aperture (NA=0.88) and used it to levitate a nanoparticle in a vacuum [Optica, 8, 1359 (2021)]. Such a system will provide opportunities for on-chip sensing. In addition, we have trapped a nanodumbbell near a surface with a separation of less than one micrometer, and used it to demonstrate an optically levitated scanning probe microscope beyond the diffraction limit. Our work will be important for studying quantum surface interactions.
Session 6: Systems with Broken Symmetry, Including Optical Angular Momentum
Session Chair: Masud Mansuripur, Wyant College of Optical Sciences (United States)
Author(s): Paulo Maia Neto, Univ. Federal do Rio de Janeiro (Brazil)
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I will present an overview of recent experiments conducted at the optical tweezers (OT) group at UFRJ, including the demonstration of a negative optical torque, axial position detection and the measurement of a fN attractive Casimir force signal in the distance range from 200 to 500 nm. I will also discuss proposals of enantioselective optical manipulation and characterization of chiral materials which are based on a theoretical model for the optical force and torque in presence of chirality.
Author(s): Sauvik Roy, Nirmalya Ghosh, Ayan Banerjee, Indian Institute of Science Education and Research Kolkata (India); Subhasish Dutta Gupta, Tata Institute of Fundamental Research (India)
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We have studied the electromagnetic focusing through a stratified medium which is placed non-symmetrically with the focusing lens having a large numerical aperture. Due to tight focusing a paraxial Gaussian beam, the highly nonparaxial focal field possess longitudinal field components. This longitudinal field component along with the transverse components generates a transverse spin angular momentum (TSAM) near the focal region. The possibility of enhancing the TSAM and the corresponding Belinfente momentum density (BSMD) by tuning the tilt angle and refractive index mismatch of the stratified medium is explored. The dependency of TSAM on the tilt angle enables us to tune certain components of TSAM along a given direction depending upon the handedness of the incident beam.
Author(s): Simon Hanna, Michael O'Donnell, Univ. of Bristol (United Kingdom)
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We present a computational study of the trapping, packing and dynamics of clusters of Rayleigh particles in optical vortices. We examine the effect of OAM on the cylindrical packing arrangements and dynamics of the clusters, drawing comparisons with macroscopic systems of beads in fluid vortices.
Author(s): Yuji Sunaba, Hokkaido Univ. (Japan); Hideki Fujiwara, Hokkai-Gakuen Univ. (Japan); Christophe Pin, Keiji Sasaki, Hokkaido Univ. (Japan)
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The ability to control nanoscale motions of nanomaterials is expected to play significant roles in various fields such as photophysics, photochemistry and biological applications. For the optical nanomanipulation, metal nanoantenna structures are widely used. These plasmonic structures can confine light into nano-sized volumes and enhance the nanoscale light-matter interactions. In this paper, we demonstrated that precise orbital rotational motion is driven by the angular momentum that is transferred from photon to plasmonic nanoantenna. We present the numerical simulation results and discussion on the mechanism of the angular momenta transfer. Then, we show the experimental results on the rotational manipulation of a nanodiamond using plasmonic trimer structure.
Author(s): Catherine M. Herne, Elaina M. Wahmann, Danae A. Evans, State Univ. of New York at New Paltz (United States)
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Levitation of birefringent objects with shape and internal birefringence offer an unusual optomechanical system with which to examine the effects of optical torques. We produce single-crystal calcite rhombohedrons that we can optically levitate and rotate. The position of levitated crystals in linearly polarized light is corner-up, the most stable orientation. The orientation angle is dependent on the optic axis, polarization direction, crystal shape, and orientation torque. The rotation is an interplay between shape and optical torques. We describe the orientation, rotation, and the axis about which they spin. We present it as a function of aspect ratio and crystal size.
Author(s): Ram Nandan Kumar, Indian Institute of Science Education and Research Kolkata (India); Subhasish Dutta Gupta, Univ. of Hyderabad (India); Nirmalya Ghosh, Ayan Banerjee, Indian Institute of Science Education and Research Kolkata (India)
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The effects of spin-orbit interaction (SOI) - which couples the spin and orbital degrees of freedom of light - are not visible macroscopically, but lead to a significant rise to several exotic phenomena in scattering, imaging, and tight focusing of light. In an optical tweezers setup, the spin and orbital angular momentum and its interaction play a significant role in the dynamics of micro-birefringent particles at a different spatial location near the focal plane. In this paper, we demonstrate the effect of spin angular momentum (SAM) in higher-order structured Gaussian beams. It has been found that the transverse distribution of the longitudinal components of the electric field in the focal plane of a microscope objective plays a crucial role in manipulating trapped microparticles in the two spatially separated Hermite-Gaussian (HG01 or HG10) lobes as well as in the intensity singularity region at the beam center.
Author(s): Mintae Chung, Karim Achouri, Olivier J. F. Martin, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
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Nano-motors driven by linearly polarized light were fabricated and measured experimentally. These structures include a plasmonic rotor embedded into a SiO2 body. The rotor geometry was optimized to reach the strongest torque using a convolutional neural network connected to a deep convolution generative adversarial network. The most promising nanostructures were fabricated with a multistep process that included ion beam etching of the rotor, followed by embodiment in SiO2. Careful optimization enabled the realization of sub-20 nm features. The nano-motors were transferred to a fluidic chamber for optical characterization, demonstrating rapid rotation speeds.
Session 7: Shaping the Flow of Information, Energy, and Momentum
Session Chair: Halina Rubinsztein-Dunlop, The Univ. of Queensland (Australia)
Author(s): Giorgio Volpe, Univ. College London (United Kingdom)
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Colloidal self-assembly has been investigated as a promising approach for the fabrication of photonic materials and devices to make, e.g., coatings, displays, and sensors for diagnostics. The final optical properties of such materials strongly depend on the interactions among the constituent colloids and on their reciprocal spatial arrangement. Photonic crystals of periodically arranged colloids for instance are optical materials that can manipulate the flow of light through controlled interference, while randomly distributed colloids can be employed to fabricate robust lasing systems where laser action is obtained thanks to the multiple scattering of light within the material. Here, I will show the self-organization of programmable random lasers from the reversible out-of-equilibrium self-assembly of colloids. Under an external light stimulus, these novel random lasers self-assemble, are responsive and show dynamic properties, such as the possibility of reconfiguring their structure and their lasing properties. These man-made lasers with their life-like features (responsiveness, reconfigurability and cooperation) are a first step towards the realization of fully animate lasers capable of independent motion and autonomous adaptation in response to external stimuli.
Author(s): J. Eduardo Lugo, Univ. de Montréal (Canada), Benemérita Univ. Autónoma de Puebla (Mexico); Miller Toledo-Solano, Benemérita Univ. Autónoma de Puebla (Mexico); Martha Alicia Palomino-Ovando, Benemérita Univ. Autónoma de Puebla (Mexico); Jocelyn Faubert, Univ. de Montréal (Canada)
Author(s): Andrei Afanasev, The George Washington Univ. (United States); Carl E. Carlson, William & Mary (United States)
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Canonical expressions for the energy-momentum tensor are obtained from symmetry transformations on the Lagrangian using the Noether construction. The result is not generally symmetric in its two indices, but can be symmetrized by adding a total derivative. The subsequent expressions for the momentum and angular momentum are the same when integrated over all space but are not in general locally the same. In particular, they are not the same for structured light, for example, for twisted photons. Hence they predict different results for forces and angular momenta induced on small test objects, in particular, for atomic rotors in ion traps. We will show, with numerical estimates of the size of the effects, testable situations where the canonical and symmetrized forms predict very different torques on small objects, over a broad range of circumstances. We will also comment on cases where the predicted radiation forces on small objects are very different based on momentum densities obtained from the canonical and symmetrized cases.
Author(s): Pawel Karpinski, Wroclaw Univ. of Science and Technology (Poland)
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The optically powered train of microparticles waveguide the light, stabilized itself and move forward due to strong optical forces. This phenomenon is similar to the soliton creation in microparticles solution, but here particles develop one after another from the reservoir in direction of light propagation, similarly to a chain developing from a spool or a train. We experimentally study the effect and numerically evaluate the forces acting on microparticles in the chain. We find different regimes of behavior depending on the microparticles size.
Author(s): Masud Mansuripur, Wyant College of Optical Sciences (United States)
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In optical experiments involving a single photon that takes alternative paths through an optical system and ultimately interferes with itself (e.g., Young's double-slit experiment, Mach-Zehnder interferometer, Sagnac interferometer), there are fundamental connections between the linear and angular momenta of the photon on the one hand, and the inability of an observer to determine the path taken by the photon through the system on the other hand. In this presentation, we examine the arguments that relate the photon momenta (through the Heisenberg uncertainty principle) to the "which path" question at the heart of quantum mechanics.
Author(s): Kamran Akbari, Valerio Di Giulio, ICFO - Institut de Ciències Fotòniques (Spain); Javier Garcia de Abajo, ICFO - Institut de Ciències Fotòniques (Spain), ICREA - Institució Catalana de Recerca i Estudis Avançats (Spain)
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Light is routinely used to steer the motion of atoms in free space, enabling cooling and trapping of matter waves through ponderomotive interaction and Doppler-mediated photon scattering. In parallel, optical interaction with free electrons has recently emerged as a powerful way to modulate the electron wave function for applications in ultrafast electron microscopy. Here, we combine these two worlds by theoretically demonstrating that matter waves can be optically manipulated by inelastic interaction with optical fields, allowing us to modulate the translational wave function and produce temporally and spatially compressed atomic beam pulses.
Session 8: Precision Measurement Including Testing Fundamental Physics I
Session Chair: David C. Moore, Yale Univ. (United States)
Author(s): Christian M. Pluchar, Aman R. Agrawal, Charles A. Condos, Wyant College of Optical Sciences (United States); Jon Pratt, Stephan Schlamminger, National Institute of Standards and Technology (United States); Dalziel Wilson, Wyant College of Optical Sciences (United States)
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We present a new class of ultra-high-Q nanomechanical resonators based on torsion modes of high-stress nanoribbons, and explore their application for quantum optomechanics experiments and precision optomechanical sensing. Specifically, we show that nanoribbons made of high stress silicon nitride support torsion modes which are naturally soft-clamped, yielding dissipation dilution factors as high as 10^4 and Q factors as high as 10^8 for the fundamental mode. We show that these modes can be read out with optical lever measurements with an imprecision below that at the standard quantum limit, paving the way for a new branch of torsional quantum optomechanics. We also show that nanoribbons can be mass-loaded without changing their torsional Q factor. We use this strategy to engineer a chip-scale torsion balance with an damping rate of 10 micro-hertz. We use this torsion balance as a clock gravimeter to sence micro-g fluctuation in the local gravitational field strength.
Author(s): Zhiyuan (Aaron) Wang, Shelby Klomp, George P. Winstone, Daniel H. Grass, Andrew Laeuger, Northwestern Univ. (United States); Greg Felsted, Peter J. Pauzauskie, Univ. of Washington (United States); Jacob Sprague, Nancy Aggarwal, Shane L. Larson, Vicky Kalogera, Andrew Geraci, Northwestern Univ. (United States)
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We present the first experimental optical trapping of ytterbium-doped sodium yttrium fluoride (Yb:NaYF4) hexagonal microdisks with a dual-beam dipole trap. These high-aspect-ratio hexagonal microdisks exhibit reduced photon recoil heating due to light scattering while allowing for 10s of kHz mechanical frequencies. These features make them good candidates as force sensors for the Levitated Sensor Detector (LSD) project, which detects high-frequency gravitational waves above the region previously probed by LIGO. We discuss motional dynamics of these microdisks by showing their motional spectra in comparison with analytical and numerical models and the recent progress of 1-meter LSD prototype that is under development at Northwestern University.
Author(s): Andrew Geraci, Northwestern Univ. (United States)
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Author(s): Giorgio Gratta, Stanford Univ. (United States)
Session 9: Optical Manipulation of Matter Through Gaseous Media
Session Chair: Catherine M. Herne, State Univ. of New York at New Paltz (United States)
Author(s): Javier Marmolejo, Göteborgs Univ. (Sweden); Adriana Canales, Chalmers Univ. of Technology (Sweden); Dag Hanstorp, Göteborgs Univ. (Sweden); Ricardo Méndez-Fragoso, Univ. Nacional Autónoma de México (Mexico)
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The dream of an atomic physicist would be to have a knob to control the properties of an atom like the electron-electron repulsion, the attractive polarizability, or the angular momentum. In the case of negative ions, these properties result in Fano resonances observed in the photodetachment continuum. In this work, we show how the Directional Mie Resonances of an optically levitated water droplet are made up of a series of evolving Fano resonances identical to those in negative ions. A direct analogy to the Schrödinger equation intuitively explains the resonances and provides knobs to fully control this toy atom.
Author(s): Michael Gleichweit, Matus E. Diveky, Dominique Borgeaud dit Avocat, Mercede Azizbaig Mohajer, Ruth Signorell, ETH Zurich (Switzerland)
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In our laboratory, we developed a novel tool to investigate interfacial mass transfer processes in single aerosol particles, called Photothermal Single-Particle Spectroscopy (PSPS). In PSPS, we utilize counter-propagating optical tweezers to trap single aerosol droplets at ambient conditions and analyze the sample by combining two virtually independent methods, photoacoustic spectroscopy (PAS) and modulated Mie scattering (MMS). Having increased the sensitivity of our setup, we discovered a previously insignificant coupling between Mie scattering and the photoacoustic signal. We discuss the possible pathways of this coupling an its influence on PSPS.
Author(s): Isaac C. D. Lenton, Andrea Stöllner, Scott R. Waitukaitis, Institute of Science and Technology Austria (Austria)
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Using optical tweezers, we isolate individual aerosol particles in order to study their charging dynamics. Preliminary results suggest that the rate at which particles charge depends on material, surface area, and most importantly, the humidity of the surrounding air. We hypothesize that charging occurs due to preferential adsorption/desorption of OH- or H+ ions. Further still, when we artificially increase the number of ions surrounding our particle, we observe rapid discharging. These results could have important implications to numerous fields including cloud formation and dust storm electrification, through to pollination; anywhere micro-particle charging plays a crucial role.
Session 10: Precision Measurement Including Testing Fundamental Physics II
Session Chair: Andrew Geraci, Northwestern Univ. (United States)
Author(s): Molly Watts, Gadi Afek, Sarah Dickson, Fernando Monteiro, Luke Mozarsky, Juan Recoaro, Benjamin Siegel, Yu-Han Tseng, Jiaxiang Wang, David C. Moore, Yale Univ. (United States)
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Highly sensitive levitated optomechanical systems can be used as precise acceleration and force sensors to search for fundamental physics. Eliminating the net charge on these systems reduces the most significant coupling to external electric fields yet leaves the issue of backgrounds created by higher order multipole moments in the charge distribution of the levitated sensors. In many high sensitivity applications of levitated optomechanical sensors, dipole induced forces can be many orders of magnitude larger than the forces of interest. Thus, techniques to measure, control, and ultimately eliminate dipole generated backgrounds may be required to realize numerous experiments such as the search for millicharged particles, the exploration of new parameter space of dark matter mass with an array of levitated microspheres and possibly future work towards detection of gravitational entanglement between micron sized masses. This talk will discuss the application of controlled precessive torques to the electric dipole moment of a levitated microsphere in vacuum to reduce dipole-induced backgrounds by 2 orders of magnitude as well as work towards integrating such sensors in large arrays.
Author(s): Giorgio Gratta, Stanford Univ. (United States)
Author(s): Huizhu Hu, Zhejiang Univ. (China), Zhejiang Lab. (China); Zhenhai Fu, Zhejiang Lab. (China); Nan Li, Zhejiang Univ. (China); Xiaowen Gao, Zhejiang Lab. (China)
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Optically levitated particles in vacuum exhibit unique advantages in the development of ultrasensitive force detector. The common Coulomb force applied by an electric field to a nanoparticle with known net charge can be used as the known force to calibrate the system or as the sensing force to measure the electric field. Here we propose a method for the force detection sensitivity calibration of a levitated nanomechanical sensor based on the harmonic Coulomb force. Utilizing the measured transfer function, we obtained the force detection sensitivity spectrum from the position spectrum. Futher, by scanning the relative position between nanoparticle and parallel electrode, the three-dimensional electric field distribution is obtained. This work may provide avenue for developing optically levitated nanoparticle system into high-precision, continuous broadband electric field sensors. In the aspect of displacement calibration, we suggest and experimentally demonstrate a novel calibration method based on free-falling particles in vacuum, where the gravitational acceleration is introduced as an absolute reference. This work provides a calibration protocol with great certainty and traceability, which is significant in improving the accuracy of precision sensing based on optically levitated particles.
Author(s): Yoshihiko Arita, Univ. of St. Andrews (United Kingdom), Chiba Univ. (Japan); Stephen Simpson, Institute of Scientific Instruments of the CAS, v.v.i. (Czech Republic); Graham Bruce, Univ. of St. Andrews (United Kingdom); Pavel Zemánek, Institute of Scientific Instruments of the CAS, v.v.i. (Czech Republic); Kishan Dholakia, Univ. of St. Andrews (United Kingdom), Chiba Univ. (Japan), Yonsei Univ. (Korea, Republic of)
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In optical tweezers, reductions in the symmetry of the particle or trapping field introduce nonconservative optical forces, producing a variety of nonequilibrium effects. Here we show nonconservative optical traps in a vacuum using birefringent microspheres in linearly polarised (LP) and circularly polarised (CP) Gaussian beams. Coherent and self-sustained oscillations emerge in LP due to nonsymmetric coupling between rotational and translational degrees of freedom, while stochastic orbital rotation and coherent limit cycles arise in CP about the beam axis. These nonconservative effects play a critical role in the rotational dynamics of a levitated birefringent microsphere.
Author(s): Antonio Pontin, Hayden Fu, Tania S. Monteiro, Peter F. Barker, Univ. College London (United Kingdom)
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We will report on recent progress in our levitated optomechanics experiment. We exploit a coherent scattering approach which has allowed a significant acceleration of the field in recent years. In this setting, a tweezer levitated nanoparticle interacts with the optical field of a Fabry-Perot cavity which is driven solely by light resonantly scattered by the particle itself. The interaction with the cavity field leads to a cross-coupling of the motional degrees of freedom (DoF) in the tweezer polarization plane so that the two DoFs are mixed. We will experimentally show that away from the cavity node, where most experiments have been working, there is a “sweet spot” where competing processes prevent the cavity from mixing these DoFs. While currently in the weak coupling regime, this effect could prevent the formation of bright/dark modes when the strong coupling is reached.
Author(s): Ryan C. Ng, Institut Català de Nanociència i Nanotecnologia (ICN2) (Spain); Guillermo Arregui, DTU Fotonik (Denmark); Guilhem Madiot, Institut Català de Nanociència i Nanotecnologia (ICN2) (Spain); Marcus Albrechtsen, DTU Fotonik (Denmark); Omar Florez, Institut Català de Nanociència i Nanotecnologia (ICN2) (Spain); Søren Stobbe, DTU Fotonik (Denmark); Clivia M. Sotomayor-Torres, David García, Institut Català de Nanociència i Nanotecnologia (ICN2) (Spain)
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We explore Anderson-localized cavity optomechanics in a two-dimensional optomechanical platform: a waveguide etched in a suspended silicon membrane with an air slot. Inherent, unavoidable fabrication imperfections induce sufficient backscattering to realize Anderson-localized optical modes which can be driven to enable phonon lasing via optomechanical back-action. We observe mechanical lasing up to 6.8 GHz that results from confinement of the mechanical mode. The role of disorder in cavity optomechanics has thus far been largely overlooked, though our results indicate that it can have a decisive impact on device functionality and opens perspectives for studies of multiple scattering and Anderson localization of bosonic excitations with parametric coupling to mechanical degrees of freedom.
Session 11: Near-Field Micromanipulation, Plasmonic, and Nanoparticle Trapping
Session Chair: Rubén Ramos-García, Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico)
Author(s): Sen Yang, Joshua A. Allen, Institute of Nanoscale Science and Engineering, Vanderbilt Univ. (United States); Chuchuan Hong, Vanderbilt Univ. (United States); Kellen P. Arnold, Institute of Nanoscale Science and Engineering, Vanderbilt Univ. (United States); Sharon M. Weiss, Justus C. Ndukaife, Vanderbilt Univ. (United States)
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We have proposed and systematically studied a cascaded bowtie photonic crystal nanobeam system that can achieve multiplexed long-range electrohydrodynamic transport and optical trapping of nanoscale particles. Ultra-high quality factor and ultra-low mode volume has been demonstrated, providing a strong field gradient ideal for trapping sub-20 nm particles. Combined with an applied alternating current electric field, the localized water absorption induces the electrothermal flow that can efficiently transport nanoparticles to the vicinity of a given bowtie region by switching the input wavelength. We envision this system will be promising in many fields, including single molecule characterization and assembly of single photon emitters.
Author(s): Martin Fränzl, Frank Cichos, Univ. Leipzig (Germany)
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The manipulation of micro- and nano-objects is of great technological significance to construct new materials, manipulate tiny amounts of liquids in fluidic systems, or detect minute concentrations of analytes. It is commonly approached by the generation of potential energy landscapes, for example, with optical fields. Here we show that strong hydrodynamic boundary flows enable the trapping and manipulation of nano-objects near surfaces. These thermo-osmotic flows are induced by modulating the van der Waals interaction at a solid-liquid interface with optically induced temperature fields. We use a thin gold film on a glass substrate to provide localized but reconfigurable point-like optical heating. Convergent boundary flows with velocities of tens of micrometres per second are observed and substantiated by a quantitative physical model. The hydrodynamic forces acting on suspended nanoparticles and attractive van der Waals or depletion induced forces enable precise positioning and guiding of the nanoparticles. Fast multiplexing of flow fields further provides the means for parallel manipulation of many nano-objects. Our findings have direct consequences for the field of plasmonic nano-tweezers as well as other thermo-plasmonic trapping schemes and pave the way for a general scheme of nanoscopic manipulation with boundary flows. [1] Fränzl, M. & Cichos, F. Hydrodynamic manipulation of nano-objects by optically induced thermo-osmotic flows. Nat Commun 13, 656 (2022).
Author(s): Jérôme Wenger, Institut Fresnel, Aix Marseille Univ. (France); Quanbo Jiang, Prithu Roy, Jean-Benoit Claude, Aix-Marseille Univ. (France)
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Optical nanoantennas require accurate nanoscale positioning of the source at the plasmonic hotspot. Here, we use plasmonic nanoantennas to simultaneously trap single colloidal quantum dots and enhance their photoluminescence. The nano-optical trapping automatically locates the quantum emitter at the nanoantenna hotspot without further processing. Our dedicated nanoantenna design achieves a high trap stiffness, together with a relatively low trapping power of 2 mW/µm². The emission from the nanoantenna-trapped single quantum dot shows increased brightness, reduced blinking, shortened lifetime and a clear antibunching demonstrating single photon emission. Combining nano-optical tweezers with plasmonic enhancement is a promising route for spectroscopy of single nano-objects.
Author(s): Peter Q. Liu, Puspita Paul, Univ. at Buffalo (United States)
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We show that graphene nanoribbons (GNR) with tunable mid-infrared (MIR) plasmonic resonances can be utilized to form an electrically controlled plasmonic conveyor belt network to simultaneously and independently trap and transport multiple nanoscale objects with high performance. Furthermore, such a GNR plasmonic conveyor belt network can induce tunable bipolar (i.e., trapping or repulsive) optical gradient forces on nanoscale objects made of materials with strong permittivity dispersions in the MIR spectral region. The tunable bipolar optical forces can be exploited to achieve selective filtering, sorting and fractionation of nanoscale objects in a mixture based on their material compositions and/or microscopic structures.
Session 12: Statistical Mechanics of Small Systems
Session Chair: Gabriel C. Spalding, Illinois Wesleyan Univ. (United States)
Author(s): Charles M. Reichhardt, Los Alamos National Lab. (United States)
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We show that self-driven particles coupled to a periodic obstacle array exhibit active matter commensuration effects that are absent in the Brownian limit. As the obstacle size is varied for sufficiently large activity, a series of commensuration effects appear in which the motility induced phase separation produces commensurate crystalline states, while for other obstacle sizes we find frustrated or amorphous states. The commensuration effects are associated with peaks in the amount of sixfold ordering and the maximum cluster size. When a drift force is added to the system, the mobility contains peaks and dips similar to those found in transport studies for commensuration effects in superconducting vortices and colloidal particles. In the low density limit we also consider directional locking effects where active particles prefer to move along certain symmetry directions of the substrate. In the dense limit for both active and passive particles we find directional clogging effects where the flow along certain directions can clog easily but the system is less susceptible to clogging for flow along other directions. We discuss how our system could be realized using active or passive colloidal particles coupled to periodic optical arrays or to microfabricated pillar arrays.
Author(s): Sarangi Suresh, Lokesh Muruga, Rahul Vaippully, Gokul Nalupurackal, Srestha Roy, Basudev Roy, Indian Institute of Technology Madras (India)
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Up-converting particles (UCP) absorb wavelengths in IR region and emit light in visible region by multiphoton absorption process. When optically trapped with 975 nm laser, these particles show active Hot Brownian Motion (HBM) due to the temperature difference created across the particle by the trapping laser. This is akin to an active particle optically confined in a tweezers with properly oriented motion. However, the activity vanishes when trapped with 1064 nm laser. We carefully maneuver the activity dependence of UCPs on laser wavelength to build a Stirling engine. A Stirling cycle consists of an isothermal expansion followed by isochoric cooling, isothermal compression and isochoric heating. Here, activity of the UCP in an optical trap is analogous to effective temperature which is controlled by the 975 nm laser. Whereas, the confinement of the trapped particle is similar to volume which can be altered by changing the trap stiffness of the 1064 nm laser trap. We first trap a UCP simultaneously with 1064 nm laser and 975 nm laser. Gradually decreasing 1064 nm laser power keeping 975 nm laser power constant decreases the trap stiffness resulting in less confinement of the UCP keeping the activity constant. This process is considered as isothermal expansion. There can also be another process where 975 nm laser power is changed leaving 1064 nm laser power constant. We explore all these processes towards the Stirling cycle.
Author(s): Danika R. Luntz-Martin, Dinesh K. Bommidi, Kai Zhang, Andrea D. Pickel, A. Nick Vamivakas, Univ. of Rochester (United States)
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Optically trapped nanoparticles can be used to explore heat conduction in gases. Heat conduction can be modeled using Fourier’s law when the mean-free path (MFP) of the gas molecules is short compared to the size of the heat source. When the MFP of the gas is larger than the size of the heated nanoparticle a nanoscopic approach which considers the gas’s interactions is needed. We use nanodiamonds with nitrogen-vacancy centers to measure the temperature of a trapped nanoparticle and observe both continuum (Fourier) and sub-continuum regions of heat conduction and the transition between them.
Author(s): Lars Forberger, Robert G. Felsted, Univ. of Washington (United States); Danika R. Luntz-Martin, A. Nick Vamivakas, Univ. of Rochester (United States); Peter J. Pauzauskie, Univ. of Washington (United States)
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Negatively charged nitrogen-vacancy (NV) centers in diamond are a promising material for many applications in quantum systems, but photothermal heating limits their utility, especially under high laser irradiances. A combination of diamonds with NV defects and the laser cooling material ytterbium-doped sodium-yttrium-fluoride (Yb:NaYF) can offset detrimental photothermal heating. We present novel preparation methods for generating NV diamond/α-NaYF composite materials and the characterization of their thermal behavior. Calculations of Mie resonances and whispering gallery modes allow for the formulation of material design goals for enhanced cooling.
Author(s): Xiaojing Xia, Lawrence Berkeley National Lab. (United States); Rachel Gariepy, Robert G. Felsted, Univ. of Washington (United States); Ayelet Teitelboim, Emory M. Chan, Lawrence Berkeley National Lab. (United States); Peter J. Pauzauskie, Univ. of Washington (United States)
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A novel design for polystyrene microspheres coated in Yb-doped NaYF upconverting nanoparticles is proposed. These microspheres show promise to realize radiation balanced lasing due to the dual purpose of the nanoparticles: as gain media and as an optical refrigeration source. Nanoparticles doped with a range of concentrations were fabricated, and their cooling capabilities were tested via non-contact methods such as photoluminescence analysis and cold Brownian motion examination while the microsphere is trapped by a laser tweezer. Microspheres coated with 8% and 10% Yb-doped nanoparticles show potential for local cooling at the surface, as well as reduced heating of their aqueous surroundings.
Author(s): Seung Ju Yoon, Da In Song, KAIST (Korea, Republic of), LG Display (Korea, Republic of); Jungmin Lee, KAIST (Korea, Republic of), SAMSUNG Electronics Co., Ltd. (Korea, Republic of); Myung-Ki Kim, Korea Univ. (Korea, Republic of); Yong-Hee Lee, KAIST (Korea, Republic of); Chang-Kyu Kim, Korea Polytechnic Univ. (Korea, Republic of)
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The hopping of a nanoparticle between two adjacent potential wells is a fundamental process in various physical, chemical, and biological phenomena. However, it is difficult to implement an experimental measure to study this process. We propose a 3D tapered metallic nanoantenna illuminated by two lasers: a continuous-wave (CW) laser for trapping a nanoparticle and a femtosecond laser for generating a background-free second harmonic signal. We controlled the landscape of the double-well potential by combining the gap size of a nanoantenna and optical pump power. The hopping of trapped nanoparticles over the central potential barrier was directly monitored and analyzed.
Session 13: Extensions of the OTOM Toolkit
Session Chair: Yuebing Zheng, The Univ. of Texas at Austin (United States)
Author(s): Jingang Li, Univ. of California, Berkeley (United States)
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Optical tweezers are extensively applied for numerous applications. However, optical tweezers are still subject to potential photo- and photothermal damages to fragile objects and are mostly used in fluidic environments. In this talk, I will present our recent research on developing novel optical techniques for the noninvasive trapping of objects and manipulating colloidal particles on solid substrates. These features will bring new possibilities in many fields, including biology, microelectronics, and nanophotonics.
Author(s): Antonio Ciarlo, Giuseppe Pesce, Univ. degli Studi di Napoli Federico II (Italy); Fatemeh Kalantarifard, Technical Univ. of Denmark (Denmark); Parviz Elahi, Bogaziçi Üniv. (Turkey); Agnese Callegari, Giovanni Volpe, Göteborgs Univ. (Sweden); Antonio Sasso, Univ. degli Studi di Napoli Federico II (Italy)
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Intracavity optical tweezers are a powerful tool to trap microparticles in water using the nonlinear feedback effect produced by the particle motion when it is trapped inside the laser cavity. In such systems two configurations are possible: a single-beam configuration and counterpropagating one. A removable isolator allows to switch between these configurations by suppressing one of the beams. Trapping a particle in the counterpropagating configuration, the measure of the optical power shows a feedback effect for each beam, that is present also when the two beams are misaligned and the trapped particle periodically jumps between them.
Author(s): Debabrata Goswami, Indian Institute of Technology Kanpur (India)
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Typical single-beam optical tweezers that use continuous wave (CW) lasers for trapping microscopic particles can be explained by force balancing the light pressure from a tightly focused laser beam. Presently, there is a surge in the use of high-repetition-rate femtosecond lasers for single-beam optical trapping research. There are certain differences between the femtosecond laser tweezers and the CW tweezers, e.g., in the sensitive detection of background free two-photon fluorescence. The instantaneous trapping potential is due to the high peak power of each laser pulse, while the sustained stable trapping results from the high repetition rate of the successive pulses. Simulating real-time scenarios for predicting optical trapping behavior continues to be a challenging problem. However, the capability and usefulness of the optical tweezers for both CW and pulsed lasers are well established. For a tightly focused beam as used in optical tweezers, cumulative heating can occur despite the minimum absorption cross-section of the trapping medium or the trapped particle, which reaches its maximum near the focus. A temperature gradient from the laser focal spot is thus generated outwards from the laser focus in the medium, creating a refractive index gradient across the focusing region. The refractive index attains a minimum at the focus, gradually increasing as a function of increasing distance from it. Since the trapping force and potential depend on the refractive index of the medium, the thermal effect impacts the force and potential of the trapped particle significantly. With CW lasers, computational evidence of temperature rise at the focus of optical tweezers has been measured, which, unfortunately, is not a feasible approach for ultrafast lasers, given the computational complexities. A better understanding of high photon flux induced processes and a working model of the single-beam optical tweezers that could address both CW and pulsed lasers would be ideal for uncovering the effects of this inherent thermal gradient of the optical tweezers. We have included all possible nonlinear effects arising from high photon flux interactions in the presented theoretical approach. This approach allows a coherent treatment of both CW and ultrafast cases. We have the purely thermal type nonlinear effects for the CW laser case, while for the ultrafast laser case, we include both the thermal and the Kerr type nonlinearities.
Author(s): Dasheng Lu, Univ. Autónoma de Madrid (Spain); Jorge Rubio Retama, Univ. Complutense de Madrid (Spain); Ricardo Marin, Manuel Marqués, Patricia Haro-González, Daniel Jaque, Univ. Autónoma de Madrid (Spain)
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Lanthanide-based upconverting nanoparticles (UCNPs) boast low thermal sensitivity and brightness, which, along with the difficulty in controlling individual UCNP remotely, make them less than ideal nanothermometers at the single-particle level. In this work we show how these problems can be elegantly solved using a thermoresponsive polymeric coating. Upon decorating the surface of NaYF4:Er,Yb UCNPs with poly(N-isopropylacrylamide) (PNIPAM), a >10-fold enhancement in optical forces is observed, allowing stable trapping and manipulation of a single UCNP in the physiological temperature range (20-45 ºC). This optical force improvement is accompanied by a significant enhancement of the thermal sensitivity reaching a maximum value of 7 % °C-1 at 31.5 ºC caused by the temperature-induced collapse of PNIPAM.
Author(s): Sui Yang, Univ. of California, Berkeley (United States), Arizona State Univ. (United States); Xuexin Ren, Univ. of California at Berkeley (United States); Rongkuo Zhao, Univ. of California, Berkeley (United States); Bo Wang, Fudan Univ. (China); Haokun Li, Yuan Wang, Univ. of California, Berkeley (United States); Lei Shi, Fudan Univ. (China); Xiang Zhang, Univ. of California, Berkeley (United States), The Univ. of Hong Kong (Hong Kong, China)
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Light-matter interaction in the context of optical trapping forms the fundamental basis for manipulating objects, enabling a plethora of exciting discoveries in many aspects of science and applications. To date, optical trapping has been explored exclusively on the interactions between electric field component of light and matter. Here we demonstrate the first magnetic optical trap in manipulating nano-objects in space. The potential created purely from magnetic component of light can selectively trap nanoparticles based on the optical magnetic susceptibility. Our work presents a new degree of freedom for studying fundamental light-matter interactions and nano-trapping and manipulation technologies.
Poster Session
Conference attendees are invited to view a collection of posters within the topics of Nanoscience + Engineering, Organic Photonics + Electronics, and Optical Engineering + Applications. Enjoy light refreshments, ask questions, and network with colleagues in your field. Authors of poster papers will be present to answer questions concerning their papers. Attendees are required to wear their conference registration badges to the poster session.

Poster authors, visit Poster Presentation Guidelines for set-up instructions.
Author(s): Veronica Gomez-Godinez, Huayan Li, Yixuan Kuang, Gabriel Mekis, Linda Shi, Michael W. Berns, Univ. of California, San Diego (United States)
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Astrocytes in the brain migrate to sites of injury where they can take up damaging molecules extruded from injured cells to protect neurons. The astrocytic response to cell death is critical to our understanding of ways to mitigate secondary injury from a traumatic brain injury(TBI). We previously showed that a laser could be used to induce a single cell death (photolysis) in order to monitor the surrounding astrocytic response. We found that photolysis leads to a calcium transient in surrounding astrocytes. Here we show that cells treated with the internal calcium chelator BAPTA-AM do not exhibit a transient. Similarly, cells whose endoplasmic reticulum (ER) has been depleted through blocking of the SERCA pump do not show a calcium increase. Cells treated with EGTA to chelate external calcium showed no statistical significance when compared to cells in regular medium with calcium. Therefore, it is concluded that the ER stores are largely responsible for the cytosolic calcium transient.
Author(s): Ashwini V. Bhat, Bangalore Univ. (India); Sharath Ananthamurthy, Univ. of Hyderabad (India)
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Raman spectra obtained from a living cell is complex owing to a variety of biomolecules. Different biomolecular Raman spectra differ from each other. Further challenges in such studies come from the occurrence of background peaks from the embedding matrix or the fixing chemicals of the cell. These complications can be avoided by using an optical tweezer, which spatially fixes the bare cell. We have used Raman spectroscopy, to interpret the bio molecular structural features in a trapped bacterium through enhancing the normally weak Raman signal by SERS treatment following the internal colloid method. We report on results so obtained.
Author(s): Emil A. Jensen, Murat Serhatlioglu, Airidas Žukauskas, Cihan Uyanik, Technical Univ. of Denmark (Denmark); Anne T. Hansen, Rigshospitalet (Denmark); Sadasivan Puthusserypady, Technical Univ. of Denmark (Denmark); Morten H. Dziegiel, Rigshospitalet (Denmark); Anders Kristensen, Technical Univ. of Denmark (Denmark)
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ABO blood typing methods are suffering from expensive reagents and require sensitive and label-free technologies. This study presents a multivariate analysis of human blood for ABO blood typing using Raman spectroscopy with the combination of support vector machine (SVM) classification. The Raman spectra of more than 270 blood samples are analyzed directly from whole blood in a fused silica microcapillary. SVM datasets are prepared using the pairwise spectral difference between the blood groups. Blood types are predicted by an average area under the curve (AUC) score of 0.958, showing great potential for the future of blood typing applications.
Author(s): Emelie Tornéus, Chalmers Univ. of Technology (Sweden); Caroline Adiels, Göteborgs Univ. (Sweden); Hana Šípová-Jungová, Chalmers Univ. of Technology (Sweden)
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Cell heterogeneity is an emerging challenge in cell biology and cancer therapies, requiring development of new tools for single-cell analysis. Here we report a non-contact method for single-cell profilometry based on gold nanoparticles optically trapped in 2D against the cell surface. By measuring both the translational and rotational dynamics of the trapped nanoparticle, we extract the distance of the nanoparticle from glass support and reconstruct the cell profile. The method reported opens new possibilities for single-cell studies of how living cells adapt their shape and volume to the changes in their environment.
Author(s): David Simon, Tobias Thalheim, Frank Cichos, Univ. Leipzig (Germany)
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Optically generated temperature fields offer a non-invasive option to study single macro-molecules in solution. Commonly, temperature gradients are used to induce a trapping of single molecules due to thermophoresis. Yet a manipulation of the conformation of macromolecules via the application of additional forces is difficult and commonly not possible without immobilising molecules at colloidal and substrate surfaces. Here we show that optically induced osmotic pressure gradients that are generated by an inhomogeneous concentration distribution of additional crowding agents in the solution allow for a controlled force generation causing a stretching and compression of single DNA molecules. We use a thin chromium film that is heated with a near infrared laser to induce local concentration gradients in a solution of polyethylene glycole (PEG) in water. The PEG concentration gradients in turn produce entropic depletion effects on the spatial distribution of DNA molecules in solution allowing them to drift towards the optically heated region. We show that the DNA is compressed in the heated region by forces in the femto-Newton range. We also observe a transient stretching of the DNA in the concentration gradient during its center of mass motion. We access quantitatively the acting forces due to the concentration gradients and correlate them with the observed stretching of the DNA. Feedback control of laser heating allows us to stabilise the stretching of DNA in dynamic concentration fields.
Author(s): Vatsal Joshi, Alan P. Bowling, The Univ. of Texas at Arlington (United States)
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The stochastic differential equations (SDEs) representing a bead's motion in an optical tweezer are stiff, meaning that the ratio of the bead's inertia to the viscous force from the surrounding fluid is extremely large. A scaling technique can be used to improve the computational time required to solve these SDEs numerically using adaptive SDE solvers. This work shows that the scaling technique can be used effectively without too much loss of information but with significant reduction in computational time. Experimental datasets for 2000nm, 1950nm, 990nm and 500nm diameter polystyrene beads are compared with the numerical results.
Author(s): Xiaoya Su, Frank Cichos, Univ. Leipzig (Germany)
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The Maxwell-Boltzmann distribution is a hallmark of statistical physics in thermodynamic equilibrium linking the probability density of a particle's kinetic energy to the temperature of the system that also determines its configurational fluctuations. This unique relation is lost for Hot Brownian Motion, e.g., when the Brownian particle is constantly heated to create an inhomogeneous temperature in the surrounding liquid. While the fluctuations of the particle in this case can be described with an effective temperature, it is not unique for all degrees of freedom and suggested to be different at different timescales. In this work, we report on our progress to measure the effective temperature of Hot Brownian Motion in the ballistic regime. We have constructed an optical setup to measure the displacement of a heated Brownian particle with a temporal resolution of 10 ns giving a corresponding spatial resolution of about 23 pm for a 0.92 µm PMMA particle in water. Using a gold-coated polystyrene (AuPS) particle of 2.15 µm diameter we determine the mean squared displacement of the particle over more than 6 orders of magnitude in time. Our data recovers the trends for the effective temperature at long timescales, yet shows also clear effects in the region of hydrodynamic long time tails.
Author(s): Yossif Elmadny, Bhavin Koirala, Gabriel C. Spalding, Illinois Wesleyan Univ. (United States)
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Since the early 2000s, there has been ongoing interest in the optical bottle, a light structure completely engulfing a dark focal region, with applications for cold atom trapping, super-resolution imaging, and object-cloaking. Here we systematically explore one method for bottle beam generation, involving the superposition of LG modes. In particular, we highlight how the Gouy phase shift evolves with mode number and the consequences of that evolution concerning the efficiency of constructing the three-dimensional dark capsule.
Author(s): Ikjun Hong, Chuchuan Hong, Guodong Zhu, Theodore Anyika, Justus C. Ndukaife, Vanderbilt Univ. (United States)
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We are investigating nanoscale bioparticle trapping using anapole-assisted nanotweezers supporting an enhanced electromagnetic field and spatial light confinement. The optical anapole is excited in silicon-based disks with a narrow slot with an electric field enhancement of twenty-three times, which is comparable to plasmonic cavities while overcoming detrimental photothermal heating effects. Ongoing experiments will test the limit of the size of the nanoscale biological objects that can be stably trapped.
Author(s): Sumit Yadav, Arijit K. De, Indian Institute of Science Education and Research Mohali (India)
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In this presentation, we will discuss results of optical trapping of the dielectric microparticles with ring-shaped laser beam by laser beam shaping using a liquid crystal spatial light modulator. A comparative discussion between results with converging annular beam and beam with annular intensity distribution at focus will also be presented.
Author(s): Dmytro Ivanskyi, Vladyslav M. Tkachuk, Chernivtsi National Univ. Y. Fedkovich (Ukraine)
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Carbon nanoparticles of order λ/10 with certain optical properties such as both strong absorption in UV region, luminescence in the yellow-green region of the spectrum and weak absorption at the wavelength of He-Ne laser radiation, are proposed to diagnose the distribution of optical flows in speckle fields. The advantages and disadvantages carbon nanoparticles synthesis are analyzed. A hydrothermal method was chosen for this synthesis. The scheme of the model experiment for study of carbon nanoparticles movement in the speckle field is proposed. Carbon nanoparticles are moving under the influence of gradient optical force caused by on internal energy flow in the optical field with capturing by the singularities of the field. The tracks of carbon nanoparticle motion under the action of the resulting optical force until their capture by the singularities of the field are experimentally obtained. It is shown that particles concentration and luminescence intensity differ significantly in minimum areas with and without singularities.
Author(s): Vladyslav M. Tkachuk, Chernivtsi National Univ. Y. Fedkovich (Ukraine)
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This investigation examines the behavior model of the of carbon nanoparticles in a speckle field under the influence of optical force. As a result of computer simulation, the optical parameters of carbon nanoparticles were obtained. It became possible to estimate optical force and its components: gradient, absorbing and scattering components, determined by the internal energy flows. The influence of the size of carbon nanoparticles on the ratio of optical force components for different wavelengths is analyzed. The conditions when the value of the gradient force will be significant are determined, which will specify the spatial movement of carbon nanoparticles in the minimum area with and without singularities point. The change in the position of particles in a three-dimensional field over time and their localization at the points of singularities under the action of the resulting optical force is demonstrated. It is proposed to use the concentration and space localization of carbon nanoparticles in an optical field to diagnose distant random objects.
Author(s): Zhihan Chen, Jingang Li, Yuebing Zheng, The Univ. of Texas at Austin (United States)
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We have developed a versatile platform for positioning and assembling different functional nanowires on solid substrates at an individual level. By exploiting light-induced local phase transition of surfactant layers and optical scattering forces, reconfigurable all-optical manipulation of nanowires has been achieved. Multiple-beam feedback control is integrated to further enhance the manipulation accuracy and throughput. This platform provides a new strategy to control single nanowires with different materials and lengths at high accuracy and simple optical setup, which can facilitate the development of various nanowire-based functional devices.
Author(s): Srestha Roy, Lokesh Muruga, Rahul Vaippully, Saumendra Bajpai, Privita Edwina, Basudev Roy, Indian Institute of Technology Madras (India)
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The cell membrane has fluctuations due to thermal and athermal sources. That causes the membrane to flicker. Conventionally, only the normal (perpendicular to the membrane) fluctuations are studied and then used to ascertain the membrane properties like the bending rigidity. It is here that we introduce a different concept, namely the slope fluctuations of the cell membrane which can be modelled as a gradient of the normal fluctuations. This can be studied using a new technique where a birefringent particle placed on the membrane turns in the out of plane sense, called the pitch sense. We introduce the pitch detection technique in optical tweezers relying upon asymmetric scattering from a birefringent particle under crossed polarizers. We then go on to use this pitch detection technique to ascertain the power spectral density of membrane slope fluctuations and find it to be (frequency)^(-1) while the normal fluctuations yields (frequency)^(-5/3). We also explore a different regime where the cell is applied with the drug latunculin-B which inhibits actin polymerization and find the effect on membrane fluctuations. We find that even as the normal fluctuations now become (frequency)^(-4/3), the slope fluctuations spectrum still remains (frequency)^(-1), with exactly the same coefficient as the case when the drug was not applied. Thus, this presents a convenient opportunity to study the membrane parameters like bending rigidity as a function of time after applying the drug. This would be the first time the membrane bending rigidity could be studied as a function of time upon the application of Lat-B without reverting to AFM. We also show a typical case where the bending rigidity of the membrane is studied as a function of time upon application of the drug.
Author(s): Lokesh Muruga, Rahul Vaippully, Basudev Roy, Indian Institute of Technology Madras (India)
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Atomic Force Microscopes (AFM) with 10 nm tip is employed to estimate work of adhesion at nano-scale. The AFM tip is pressed against the surface with forces around a few nano-Newtons and retracted back until it breaks from the surface. Thus estimating the work of adhesion due to this technique can be termed as “hard probing” of the surface. Whereas, we propose another configuration in which a spherical particle is trapped near the surface using a linearly polarized light and the particle attaches to the surface by work of adhesion. Here, by moving the surface in tangential direction, the particle is forced into a rolling motion. This motion can be used to estimate work of adhesion and this technique can be called “soft probing”. We used the soft probing configuration to estimate rolling work of adhesion of a birefringent 3 μm particle on a glass surface. Further, we have studied the effects of PolydimethylSiloxane (PDMS) which is a hydrophobic surface. This technique is used to probe the rolling work of adhesion of 500 nm nanodiamond bearing Nitrogen-vacancy centers which are birefringent due to the stress in the crystal. These nanodiamonds have a contact diameter as small as 50 nm because of their relatively high Young's modulus. The rolling work of adhesion estimated using our soft probing configuration is about 1 mJ/m2, while using the AFM tips to estimate work of adhesion at nanoscale yields about 50 mJ/m2.
Author(s): Pavana Siddhartha Kollipara, Jingang Li, Yuebing Zheng, The Univ. of Texas at Austin (United States)
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We report a new type of optical rotary nanomotors that are operated on a solid substrate. A thin phase-changing surfactant layer is used to modulate particle-substrate interactions to enable the rotation of light-absorbing nanoparticles. Optical rotation is achieved by the synergy of optical forces and thermocapillary forces induced by the multi-faceted geometry of nanoparticles. Being operated on solid substrates, our nanomotors can be integrated with solid-state electronics to enable the development of on-chip active devices for optoelectronic and photonic applications.
Author(s): Julio Aurelio Sarabia-Alonso, Rubén Ramos-García, Joaquín Alberto Ascencio-Rodríguez, Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico); José Gabriel Ortega-Mendoza, Univ. Tecnológica de Tulancingo (Mexico)
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We show 3D steady-state trapping and manipulation of vapor bubbles in liquids employing a low-powera continuous-wave laser using the Marangoni effect. Light absorption from photodeposited silver nanoparticles on the distal end of multi-mode optical fiber is used to produce bubbles of different diameters. The thermal effects produced by either the nanoparticles on the fiber tip or the light bulk absorption modulate the surface tension of the bubble wall and creates both longitudinal and transversal forces just like optical forces, effectively creating a 3D potential well. Using numerical simulations, we obtain expressions for the temperature profiles and present analytical expressions for the Marangoni force. In addition, using an array of three fibers with photodeposited nanoparticles is used to demonstrate the transfer of bubbles from one fiber to another by sequentially switching on and off the lasers.
Author(s): Thomas Celenza, Andy Eskenazi, Zhipeng Lu, Leah Tesfa, Lorenzo Yao-Bate, Mohsen Azadi, Matthew Campbell, Igor Bargatin, Univ. of Pennsylvania (United States)
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We report flight through levitation with no moving parts through fabrication of nanostructured films which take advantage of photophoretic forces, or light-induced motion of gas molecules to create lift. This lift force is enough to levitate structures within a light trap or directionally controlled light source such as LEDs or a laser to create “microflyers” with sensor payloads for the mesosphere and Mars, areas with little to no atmospheric data research. We are working to optimize various dimensional parameters, fabricate the optimized structures, and test them in our vacuum chamber for at various pressures.
Author(s): Pantea Dara, Mahdi Shanei, Steven Jones, Mikael Käll, Chalmers Univ. of Technology (Sweden)
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Strong flow transients can be induced around microbubbles nucleated on spatially isolated laser-heated plasmonic nanoantennas. The flow depends on the temperature gradient on the bubble surface, which is typically directed normal to the substrate surface and therefore results in a symmetric flow pattern. Based on optical force microscopy data, single particle manipulation experiments, and flow simulations, we demonstrate and discuss the possibility of creating strong directional transient flows around a microbubble by breaking the symmetry of the plasmonic nanoantenna structure. The phenomenon may provide a means for optical vectorial control of flows and particle movement in microfluidics and beyond.
Author(s): Youngsun Kim, Yuebing Zheng, The Univ. of Texas at Austin (United States)
Author(s): Theodore Anyika, Justus C. Ndukaife, Chuchuan Hong, Vanderbilt Univ. (United States)
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Conventional double nanohole optical tweezers are usually fabricated on glass substrates and trapping events are detected by monitoring small changes in transmission. However, the distribution of the enhanced electric field has a significant portion localized in the glass substrate, thereby limiting access to particles. In this work, we show that by introducing a gold reflector at the bottom of the hole, the enhanced electric field can be made fully accessible to particles and very high field enhancements could be achieved. We also demonstrate that electric field enhancement factors of up to 70 can be achieved with this platform, showing potential application as SERS substrates.
Author(s): Viktor Nascak, Anna S. Bezryadina, California State Univ., Northridge (United States)
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As the number of microplastics present in the environment continues to rise, understanding the effects of microplastics on living organisms becomes crucial. In our work, we isolate nature-found ocean microplastics through the processing of sand from Los Angeles beaches and study the behavior of microplastics under a microscope using an optical tweezer setup. Since microplastics are hard to distinguish from sand visually, they are isolated from sand through density separation. Because of the irregular shape and varying compositions of microplastics, their behavior under optical forces is nontrivial. The optical trapping information will be used to study the interaction of microplastics with ocean microorganisms.
Sunday Evening Plenary
21 August 2022 • 6:00 PM - 7:30 PM
Author(s): Michael W. Berns, Beckman Laser Institute and Medical Clinic (United States)
21 August 2022 • 6:05 PM - 6:35 PM
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It was 1966 and all I knew about lasers was that Goldfinger was going to slice James Bond in half. Then one of my professors at Cornell told me that the department had purchased a small ruby laser but did not know what to do with it and he felt it might be useful for very fine tissue ablation if coupled to a microscope. But the operating parameters of the red ruby laser made it difficult to control when focused to a small spot plus the absorption characteristics of most of the cell structures did not match the 694.3 nm wavelength of the laser. However, when the blue green argon ion laser was available, the ability to focus the pulsed beam to its diffraction limit plus the absorption properties of some cell structures (and the addition of light-absorbing dyes to these structures) allowed for precise ablation in spots less than 0.5 micrometer diameter, especially the chromosomes in live cells. When the nanosecond and picosecond 532nm and 355 nm harmonics of the NdYag lasers became available even greater precision of nanoablation was possible due to natural absorption by the target structure and/or non-linear multiphoton ablation which occurred regardless of absorption characteristics of the target. These optical systems were used (and still are) to perform subcellular surgery on any cell organelle visible with the light microscope. With Arthur Ashkin’s invention of optical traps (laser tweezers), cell biologists now had a complementary optical tool to the laser scissors and so began a renaissance in the use of light to finely alter and manipulate cells.
Quantum science and metrology (Plenary Presentation)
Author(s): Jun Ye, JILA, Univ. of Colorado (United States)
21 August 2022 • 6:45 PM - 7:15 PM
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Precise engineering of quantum states of matter and innovative laser technology are revolutionizing the performance of atomic clocks and metrology, providing new opportunities to explore emerging phenomena, test fundamental symmetry, and search for new physics. The recent work of measuring gravitational time dilation at the sub-millimeter scale highlights exciting prospects for new scientific discovery and technology development.
Nanoscience + Engineering Plenary
22 August 2022 • 8:30 AM - 10:05 AM
Session Chairs: Gennady B. Shvets, Cornell Univ. (United States), Cornelia Denz, Westfälische Wilhelms-Univ. Münster (Germany)
8:30 AM - 8:35 AM: Welcome and Opening Remarks
Author(s): Lisa V. Poulikakos, Univ. of California, San Diego (United States)
22 August 2022 • 8:35 AM - 9:10 AM
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The origin and progression of a variety of leading health challenges, encompassing Alzheimer’s disease, heart disease, fibrosis and cancer, are directly linked to changes in the presence and orientation of fibrous matter in biological tissue. Here, we leverage the unique properties of anisotropic, colorimetric metasurfaces to scale down the complex manipulation of light and selectively visualize disease-relevant fiber density and orientation in biological tissue. Starting with the example of breast cancer diagnostics, we then expand our view to the rich palette of fiber-affecting diseases where metasurfaces hold great potential as rapid, precise and low-cost tissue diagnostics with facile clinical implementation.
Author(s): Keren Bergman, Columbia Univ. (United States)
22 August 2022 • 9:20 AM - 9:55 AM
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High performance data centers are increasingly bottlenecked by the energy and communications costs of interconnection networks. Our recent work has shown how integrated silicon photonics with comb-driven dense wavelength-division multiplexing can scale to realize Pb/s chip escape bandwidths with sub-picojoule/bit energy consumption. We use this emerging interconnect technology to introduce the concept of embedded photonics for deeply disaggregated architectures. Beyond alleviating the bandwidth/energy bottlenecks, the new architectural approach enables flexible connectivity tailored for specific applications.
Conference Chair
Univ. of St. Andrews (United Kingdom)
Conference Chair
Illinois Wesleyan Univ. (United States)
Program Committee
Ashley R. Carter
Amherst College (United States)
Program Committee
Univ. of Victoria (Canada)
Program Committee
State Univ. of New York at New Paltz (United States)
Program Committee
Wyant College of Optical Sciences (United States)
Program Committee
James Millen
King's College London (United Kingdom)
Program Committee
David C. Moore
Yale Univ. (United States)
Program Committee
Vanderbilt Univ. (United States)
Program Committee
Lehigh Univ. (United States)
Program Committee
Univ. of California, San Diego (United States)
Program Committee
Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico)
Program Committee
The Univ. of Queensland (Australia)
Program Committee
Nick Vamivakas
Univ. of Rochester (United States)
Program Committee
Univ. Nacional Autónoma de México (Mexico)
Program Committee
The Univ. of Texas at Austin (United States)