scholarly journals Plasmonic linear nanomotor using lateral optical forces

2020 ◽  
Vol 6 (45) ◽  
pp. eabc3726
Author(s):  
Yoshito Y. Tanaka ◽  
Pablo Albella ◽  
Mohsen Rahmani ◽  
Vincenzo Giannini ◽  
Stefan A. Maier ◽  
...  
Keyword(s):  
Laser Beam ◽  
Incident Light ◽  
Lateral Force ◽  
Diffraction Limit ◽  
Propagation Direction ◽  
Optical Force ◽  
Optical Forces ◽  
Incident Laser ◽  
New Class ◽  
Force Direction

Optical force is a powerful tool to actuate micromachines. Conventional approaches often require focusing and steering an incident laser beam, resulting in a bottleneck for the integration of the optically actuated machines. Here, we propose a linear nanomotor based on a plasmonic particle that generates, even when illuminated with a plane wave, a lateral optical force due to its directional side scattering. This force direction is determined by the orientation of the nanoparticle rather than a field gradient or propagation direction of the incident light. We demonstrate the arrangements of the particles allow controlling the lateral force distributions with the resolution beyond the diffraction limit, which can produce movements, as designed, of microobjects in which they are embedded without shaping and steering the laser beam. Our nanomotor to engineer the experienced force can open the door to a new class of micro/nanomechanical devices that can be entirely operated by light.

scholarly journals Enhancement of optical force acting on vesicles via the binding of gold nanoparticles

2019 ◽  
Vol 6 (5) ◽  
pp. 190293 ◽  
Author(s):  
Yumeki Tani ◽  
Takashi Kaneta
Keyword(s):  
Gold Nanoparticles ◽  
Light Scattering ◽  
Laser Beam ◽  
Binding Constant ◽  
Electrostatic Interactions ◽  
Propagation Direction ◽  
Optical Force ◽  
Surface Charges ◽  
Scattering Force ◽  
The Relationship

Here we found that gold nanoparticles (AuNPs) enhance the optical force acting on vesicles prepared from phospholipids via hydrophobic and electrostatic interactions. A laser beam was introduced into a cuvette filled with a suspension of vesicles and it accelerated them in its propagation direction via a scattering force. The addition of the AuNPs exponentially increased the velocity of the vesicles as their concentration increased, but polystyrene particles had no significant impact on velocity in the presence of AuNPs. To elucidate the mechanism of the increased velocity, the surface charges in the vesicles and the AuNPs were controlled; the surface charges of the vesicles were varied via the use of anionic, cationic and neutral phospholipids, whereas AuNPs with positive and negative charges were synthesized by coating with citrate ion and 4-dimethylaminopyridine, respectively. All vesicles increased the velocity at different degrees depending on the surface charge. The vesicles were accelerated more efficiently when their charges were opposite those of the AuNPs. These results suggested that hydrophobic and electrostatic interactions between the vesicles and the AuNPs enhanced the optical force. By accounting for the binding constant between the vesicles and the AuNPs, we proposed a model for the relationship between the concentration of the AuNPs and the velocity of the vesicles. Consequently, the increased velocity of the vesicles was attributed to the light scattering that was enhanced when AuNPs were adsorbed onto the vesicles.

scholarly journals Lateral forces on circularly polarizable particles near a surface

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Francisco J. Rodríguez-Fortuño ◽  
Nader Engheta ◽  
Alejandro Martínez ◽  
Anatoly V. Zayats
Keyword(s):  
Light Propagation ◽  
Polarized Light ◽  
Optical Force ◽  
Optical Forces ◽  
Circularly Polarized Light ◽  
Force Direction ◽  
Electromagnetic Momentum ◽  
Nanophotonic Structures ◽  
And Control ◽  
Light Beams

Abstract Optical forces allow manipulation of small particles and control of nanophotonic structures with light beams. While some techniques rely on structured light to move particles using field intensity gradients, acting locally, other optical forces can ‘push’ particles on a wide area of illumination but only in the direction of light propagation. Here we show that spin–orbit coupling, when the spin of the incident circularly polarized light is converted into lateral electromagnetic momentum, leads to a lateral optical force acting on particles placed above a substrate, associated with a recoil mechanical force. This counterintuitive force acts in a direction in which the illumination has neither a field gradient nor propagation. The force direction is switchable with the polarization of uniform, plane wave illumination, and its magnitude is comparable to other optical forces.

Influences of the Inserted Angle of an Optical Fiber for an Optical Trapping

2012 ◽  
Vol 523-524 ◽  
pp. 1053-1058
Author(s):  
Nobuyuki Watanabe ◽  
Kozo Taguchi
Keyword(s):  
Laser Beam ◽  
Optical Fiber ◽  
Optical Trapping ◽  
Axial Direction ◽  
Optical Force ◽  
Radius Of Curvature ◽  
Optical Forces ◽  
System A ◽  
Sample Chamber ◽  
Pulling Force

Biological cell could be trapped by a single laser beam from an optical fiber end inserted at an angle to a sample chamber. We have already developed an optical trapping system. A temperature stabilized 1480nm cw diode laser was used as the light source. The fiber end had a hemispherical micro-lens with 5μm radius of curvature for focusing the laser beam. These trapping fibers were inserted into a sample cell at an angle. The microsphere, 10μm diameter particle (refractive index 1.4), could be trapped. We theoretically analyzed the optical forces exerted on a microsphere by laser beams. The optical force on a microsphere divides itself into two components, the force in the beam axial direction of the light and a transverse force. The transverse optical force acted to pull the sphere back. We investigated the relation between the pulling force and the inserted angle of an optical fiber into a sample chamber. The microsphere is trapped at the point where the horizontal directed optical forces are balanced. We theoretically verified that the inserted angle of an optical fiber into a sample chamber was important parameter. It was found that a small inserted angle produced a weak pulling force.

scholarly journals 1178 J, 527 nm near diffraction limited laser based on a complete closed-loop adaptive optics controlled off-axis multi-pass amplification laser system

2021 ◽  
Vol 9 ◽  
Author(s):  
Deen Wang ◽  
Xin Zhang ◽  
Wanjun Dai ◽  
Ying Yang ◽  
Xuewei Deng ◽  
...  
Keyword(s):  
Laser Beam ◽  
Adaptive Optics ◽  
Closed Loop ◽  
Focal Spot ◽  
Beam Quality ◽  
Laser System ◽  
Diffraction Limit ◽  
Kdp Crystal ◽  
Main Amplifier

Abstract A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics (AO) controlled off-axis multi-pass amplification laser system. Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier, a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62% conversion efficiency, 1178 J and beam quality of 7.93 times the diffraction limit (DL). By using a complete closed-loop AO configuration, the static and dynamic wavefront distortions of the laser system are measured and compensated. After correction, the diameter of the circle enclosing 80% energy is improved remarkably from 7.93DL to 1.29DL. The focal spot is highly concentrated and the 1178 J, 527 nm near diffraction limited laser is achieved.

Boundary value conditions for wave fronts in reaction-diffusion systems

1984 ◽  
Vol 99 (1-2) ◽  
pp. 127-136 ◽  
Author(s):  
J. M. Fraile ◽  
J. Sabina
Keyword(s):  
Wave Front ◽  
Reaction Diffusion ◽  
Propagation Direction ◽  
Dirichlet Problems ◽  
Reaction Diffusion Systems ◽  
New Class ◽  
Diffusion Systems ◽  
Front Solutions ◽  
Distinguished Boundary ◽  
Directional Wave

SynopsisIn this paper, we introduce a new class of solutions of reaction-diffusion systems, termed directional wave front solutions. They have a propagating character and the propagation direction selects some distinguished boundary points on which we can impose boundary conditions. The Neumann and Dirichlet problems on these points are treated here in order to prove some theorems on the existence of directional wave front solutions of small amplitude, and to partially establish their asymptotic behaviour.

INVESTIGATION OF PECULIARITIES OF LIGHT SCATTERING BY NANOSTRUCTURAL CHANGES IN THE CRYSTAL LATTICE OF FERROELECTRIC BARIUM SODIUM NIOBATE CRYSTAL

2004 ◽  
Vol 03 (06) ◽  
pp. 815-818 ◽  
Author(s):  
S. V. IVANOVA
Keyword(s):  
Light Scattering ◽  
Laser Beam ◽  
Beam Width ◽  
Far Field ◽  
Sodium Niobate ◽  
Incident Laser Beam ◽  
Incident Laser ◽  
Elastic Light Scattering ◽  
Temperature Range ◽  
Thermal Changes

Thermal changes of light scattering images in the far-field were observed under steady illumination by an incident laser beam of finite beam width on barium sodium niobate crystals in the temperature range of 20–500°C. Different patterns of light scattering in far-field were observed — from striped to round-like form with dependence on temperature, conditions of grown, direction of beam and polarization. The round-like form was observed on cooling from 450°C to 240°C. Striped forms of light scattering were observed below 200°C. Correlation of the behavior of elastic light scattering was observed in this temperature range.

scholarly journals Flow with nanoparticle clustering controlled by optical forces in quartz glass nanoslits

2019 ◽  
Vol 23 (11) ◽  
Author(s):  
Tetsuro Tsuji ◽  
Yuki Matsumoto ◽  
Satoyuki Kawano
Keyword(s):  
Flow Control ◽  
Quartz Glass ◽  
Target Material ◽  
Optical Force ◽  
Control Technique ◽  
Intermittent Flow ◽  
Channel Height ◽  
Optical Forces ◽  
Sudden Contraction ◽  
Nanofluidic Devices

Abstract In this paper, we demonstrate nanoparticle flow control using an optical force in a confined nanospace. Using nanofabrication technologies, all-quartz-glass nanoslit channels with a sudden contraction are developed. Because the nanoslit height is comparable to the nanoparticle diameter, the motion of particles is restricted in the channel height direction, resulting in almost two-dimensional particle motion. The laser irradiates at the entrance of the sudden contraction channel, leading the trapped nanoparticles to form a cluster. As a result, the translocation of nanoparticles into the contraction channel is suppressed. Because the particle translocation restarts when the laser irradiation is stopped, we can control the nanoparticle flow into the contraction channel by switching the trapping and release of particles, realizing an intermittent flow of nanoparticles. Such a particle flow control technique in a confined nanospace is expected to improve the functions of nanofluidic devices by transporting a target material selectively to a desired location in the device.

scholarly journals Long-distance optical pulling of nanoparticle in a low index cavity using a single plane wave

2020 ◽  
Vol 6 (21) ◽  
pp. eaaz3646 ◽  
Author(s):  
E. Lee ◽  
T. Luo
Keyword(s):  
Plane Wave ◽  
Incident Light ◽  
Propagation Direction ◽  
Core Shell ◽  
Long Distance ◽  
Single Plane ◽  
Practical Applications ◽  
Multipole Analysis ◽  
Cavity Structure ◽  
Pulling Force

Optical pulling force (OPF) can make a nanoparticle (NP) move against the propagation direction of the incident light. Long-distance optical pulling is highly desired for nano-object manipulation, but its realization remains challenging. We propose an NP-in-cavity structure that can be pulled by a single plane wave to travel long distances when the spherical cavity wrapping the NP has a refractive index lower than the medium. An electromagnetic multipole analysis shows that NPs made of many common materials can receive the OPF inside a lower index cavity. Using a silica-Au core-shell NP that is encapsulated by a plasmonic nanobubble, we experimentally demonstrate that a single laser can pull the Au NP-in-nanobubble structure for ~0.1 mm. These results may lead to practical applications that can use the optical pulling of NP, such as optically driven nanostructure assembly and nanoswimmers.

A high-speed-modulated retro-reflector for lasers using an acousto-optic modulator

2003 ◽  
Vol 81 (4) ◽  
pp. 625-638 ◽  
Author(s):  
G Spirou ◽  
I Yavin ◽  
M Weel ◽  
A Vorozcovs ◽  
A Kumarakrishnan ◽  
...  
Keyword(s):  
Laser Beam ◽  
Acoustic Waves ◽  
High Speed ◽  
Incident Beam ◽  
Bragg Diffraction ◽  
Heterodyne Detection ◽  
Incident Laser Beam ◽  
Signal To Noise ◽  
Incident Laser ◽  
Acousto Optic Modulator

We have used an acousto-optic modulator (AOM) to impose a frequency-modulated signal on an incident laser beam. The incident laser beam is focussed into the AOM where it undergoes Bragg diffraction and is then retro-reflected. The diffracted beam is also retro-reflected so that it is diffracted again by the AOM and overlaps the incident beam. The overlapped beams are frequency shifted with respect to each other. These features allow us to detect the frequency-modulated signal with high signal-to-noise ratio using heterodyne detection. Since the optical setup is simple and can be made very compact, this device may be ideal for certain forms of high-speed, free-space optical communication. We demonstrate a 1 MHz data transmission rate in the Bragg regime. We measured the acceptance angle of the device and find that it is limited only by the divergence of the focussed laser beam and the divergence of the acoustic waves in the AOM crystal. We have also studied the range of acoustic frequencies and drive power of the AOM, for which the retro-reflected beam can be detected with adequate signal to noise. PACS Nos.: 42.60.–V, 42.62.Cf, 42.62.Fi, 42.79.Sz, 42.79.Hp

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