Nonlinear Double-arm Optical Tweezers for Controlling 3D Microspheres

In this paper, a new nonlinear double-arm optical tweezer combining Mach-Zenhder interferometer, objective lens and organic dye layer is proposed. Based on the ray-optical and wave optical approximations, the expression describing the separation of two trap centers and laser intensity distribution is derived. The obtained results show that the separation between two trap centers, the laser intensity distribution, trap region's area and optical trap efficiency can be controlled by tuning laser power. The proposed model is seen to be a double-arm optical tweezer for controlling 3D microsphere by optical method.

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Measurement of Trap Stiffness of Holographic Optical Tweezers with Power Spectrum Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.787.423 ◽

2013 ◽

Vol 787 ◽

pp. 423-426

Author(s):

Kai Xu ◽

Jing Li ◽

Gang Du ◽

Chun Li Zhu ◽

Peng Fei Li ◽

...

Keyword(s):

Brownian Motion ◽

Power Spectrum ◽

Optical Tweezers ◽

Laser Power ◽

Optical Trap ◽

Bottom Surface ◽

Sample Cell ◽

Spectrum Method ◽

Holographic Optical Tweezers ◽

Power Spectrum Method

A microsphere trapped by optical tweezers moves according to the Brownian motion law, which can be described by the Langevin equation. Based on it, a quadrant photodiode (QD) is used to track the displacement of the microsphere with a diameter of 2.5um trapped by holographic optical tweezers, and power spectrum method is adopted to obtain radial trap stiffness. Experiments show that the trap stiffness increases with the increase of the laser power, and decreases as the distance between the optical trap and the inside bottom surface of the sample cell increases.

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Influence of Laser Intensity Fluctuation on Single-Cesium Atom Trapping Lifetime in a 1064-nm Microscopic Optical Tweezer

Applied Sciences ◽

10.3390/app10020659 ◽

2020 ◽

Vol 10 (2) ◽

pp. 659

Author(s):

Rui Sun ◽

Xin Wang ◽

Kong Zhang ◽

Jun He ◽

Junmin Wang

Keyword(s):

Optical Tweezers ◽

Intensity Fluctuation ◽

Laser Intensity ◽

Single Photon ◽

Optical Tweezer ◽

Optical Modulator ◽

Quantum Bits ◽

The Time Domain ◽

The Impact ◽

Coherent Manipulation

An optical tweezer composed of a strongly focused single-spatial-mode Gaussian beam of a red-detuned 1064-nm laser can confine a single-cesium (Cs) atom at the strongest point of the light intensity. We can use this for coherent manipulation of single-quantum bits and single-photon sources. The trapping lifetime of the atoms in the optical tweezers is very short due to the impact of the background atoms, the parametric heating of the optical tweezer and the residual thermal motion of the atoms. In this paper, we analyzed the influence of the background pressure, the trap frequency of optical tweezers and the laser intensity fluctuation of optical tweezers on the atomic trapping lifetime. Combined with the external feedback loop based on an acousto-optical modulator (AOM), the intensity fluctuation of the 1064-nm laser in the time domain was suppressed from ±3.360% to ±0.064%, and the suppression bandwidth in the frequency domain reached approximately 33 kHz. The trapping lifetime of a single-Cs atom in the microscopic optical tweezers was extended from 4.04 s to 6.34 s.

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Pinhole Optical Tweezers: Extending the Photobleaching Lifetime in the Presence of an Optical Trap by Wavefront Engineering

10.1101/808352 ◽

2019 ◽

Author(s):

Zheng Zhang ◽

Joshua N. Milstein

Keyword(s):

Optical Tweezers ◽

Single Molecule ◽

Biological Sample ◽

Near Infrared ◽

Optical Trap ◽

Organic Dye ◽

Single Molecule Fluorescence ◽

Low Intensity ◽

Intensity Region ◽

Ir Light

ABSTRACTWe present a new method for combining optical tweezers with single-molecule fluorescence in an engineered geometry we have coined a ‘pinhole’ optical trap. By utilizing an appropriately constructed Laguerre-Gaussian (LG) or ‘donut’ beam, and applying force along the axis of the trapping laser, one can maintain a low-intensity region of near-infrared (IR) light directly below the optical trap in which a biomolecule may be probed by both force spectroscopy and fluorescence. We show that within this region of low IR light intensity, the photobleaching lifetime of Alexa-647, an organic dye that is particularly sensitive to the high intensity trap light, can be significantly extended. This approach enables us to spatially separate the trap light from the fluorescence illumination without the need to physically separate, by many micrometers, the optical trap from the biological sample.

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Anomalous Lehmann Rotation of Achiral Nematic Liquid Crystal Droplets Trapped under Linearly Polarized Optical Tweezers

Molecules ◽

10.3390/molecules26144108 ◽

2021 ◽

Vol 26 (14) ◽

pp. 4108

Author(s):

Jarinee Kiang-ia ◽

Rahut Taeudomkul ◽

Pongthep Prajongtat ◽

Padetha Tin ◽

Apichart Pattanaporkratana ◽

...

Keyword(s):

Liquid Crystal ◽

Optical Tweezers ◽

Nematic Liquid Crystal ◽

Laser Power ◽

Optical Trap ◽

Laser Trapping ◽

Laser Trap ◽

Continuous Rotation ◽

Linearly Polarized ◽

Optical Levitation

Continuous rotation of a cholesteric droplet under the heat gradient was observed by Lehmann in 1900. This phenomenon, the so-called Lehmann effect, consists of unidirectional rotation around the heat flux axis. We investigate this gradient heat effect using infrared laser optical tweezers. By applying single trap linearly polarized optical tweezers onto a radial achiral nematic liquid crystal droplet, trapping of the droplet was performed. However, under a linearly polarized optical trap, instead of stable trapping of the droplet with slightly deformed molecular directors along with a radial hedgehog defect, anomalous continuous rotation of the droplet was observed. Under low power laser trapping, the droplet appeared to rotate clockwise. By continuously increasing the laser power, a stable trap was observed, followed by reverse directional rotation in a higher intensity laser trap. Optical levitation of the droplet in the laser beam caused the heat gradient, and a breaking of the symmetry of the achiral nematic droplet. These two effects together led to the rotation of the droplet under linearly polarized laser trapping, with the sense of rotation depending on laser power.

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New Detector Sensitivity Calibration and the Calculation of the Interaction Force between Particles Using an Optical Tweezer

Micromachines ◽

10.3390/mi9090425 ◽

2018 ◽

Vol 9 (9) ◽

pp. 425

Author(s):

Pavel Yale ◽

Jean-Michel Konin ◽

Michel Kouacou ◽

Jérémie Zoueu

Keyword(s):

Optical Tweezers ◽

Optical Trap ◽

Ccd Camera ◽

Optical Tweezer ◽

Interaction Force ◽

Sensitivity Factor ◽

Charge Coupled Device ◽

Silica Beads ◽

A Charge ◽

Different Diameters

We propose a new approach to calculate the sensitivity factor of the detector in optical tweezers. In this work, we used a charge-coupled device (CCD) camera and a quadrant photodiode (QPD) for the extraction of the various positions occupied by the trapped object (in this case, silica beads of different diameters). Image-J software and the Boltzmann statistical method were then used to estimate the sensitivity of the detector. Silica beads of diameter 0.8 µm, 2 µm, a system of 2 µm bead stuck to 4.5 µm one and another system of 2 µm beads stuck to 2 µm one, were studied. This work contributes significantly to making better calibration of the detector without taking into account the geometry of the object imprisoned in the optical trap. We further developed an approach to calculate the interaction force between two microbeads. This approach does not require any knowledge of solvent viscosity and works for all types of samples.

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Enhanced Signal-to-Noise and Fast Calibration of Optical Tweezers Using Single Trapping Events

Micromachines ◽

10.3390/mi12050570 ◽

2021 ◽

Vol 12 (5) ◽

pp. 570

Author(s):

Alexander B. Stilgoe ◽

Declan J. Armstrong ◽

Halina Rubinsztein-Dunlop

Keyword(s):

Brownian Motion ◽

Optical Tweezers ◽

Optical Trap ◽

Force Transducer ◽

Signal To Noise ◽

Likelihood Estimator ◽

Micro Fluidics ◽

Large Numbers ◽

Force Reconstruction ◽

Micron Particle

The trap stiffness us the key property in using optical tweezers as a force transducer. Force reconstruction via maximum-likelihood-estimator analysis (FORMA) determines the optical trap stiffness based on estimation of the particle velocity from statistical trajectories. Using a modification of this technique, we determine the trap stiffness for a two micron particle within 2 ms to a precision of ∼10% using camera measurements at 10 kfps with the contribution of pixel noise to the signal being larger the level Brownian motion. This is done by observing a particle fall into an optical trap once at a high stiffness. This type of calibration is attractive, as it avoids the use of a nanopositioning stage, which makes it ideal for systems of large numbers of particles, e.g., micro-fluidics or active matter systems.

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ORIENTATING MANIPULATION OF CYLINDRICAL PARTICLES WITH OPTICAL TWEEZERS

Journal of Nonlinear Optical Physics & Materials ◽

10.1142/s021886350800438x ◽

2008 ◽

Vol 17 (04) ◽

pp. 387-394 ◽

Cited By ~ 1

Author(s):

XIUDONG SUN ◽

XUECONG LI ◽

JIANLONG ZHANG

Keyword(s):

Escherichia Coli ◽

Carbon Nanotubes ◽

Laser Beam ◽

Optical Tweezers ◽

Optical Trap ◽

Polarization Direction ◽

Beam Shape ◽

E Coli ◽

Potential Applications ◽

Cylindrical Particles

Orientating manipulations of cylindrical particles were performed by optical tweezers. Vertical and horizontal manipulations of Escherichia coli (E. coli) were carried out by changing the trapping depth and the focused laser beam shape. It was found that carbon nanotubes bundles (CNTBs) could be rotated in the linear polarized optical trap until it orientated its long axis along the linear polarization direction of the laser beam. However, E.coli could not be orientated in this way. Corresponding mechanisms were discussed based on the anisomeric electric characters of CNTBs. These orientation technologies of cylindrical objects with optical trap have potential applications in assembling nano-electric devices.

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Assembly of multicomponent structures from hundreds of micron-scale building blocks using optical tweezers

Microsystems & Nanoengineering ◽

10.1038/s41378-021-00272-z ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Jeffrey E. Melzer ◽

Euan McLeod

Keyword(s):

Optical Tweezers ◽

Three Dimensional ◽

Building Blocks ◽

Optical Tweezer ◽

Device Fabrication ◽

Positional Accuracy ◽

Component Structure ◽

Material Development ◽

Critical Process Parameters ◽

Optical Positioning

AbstractThe fabrication of three-dimensional (3D) microscale structures is critical for many applications, including strong and lightweight material development, medical device fabrication, microrobotics, and photonic applications. While 3D microfabrication has seen progress over the past decades, complex multicomponent integration with small or hierarchical feature sizes is still a challenge. In this study, an optical positioning and linking (OPAL) platform based on optical tweezers is used to precisely fabricate 3D microstructures from two types of micron-scale building blocks linked by biochemical interactions. A computer-controlled interface with rapid on-the-fly automated recalibration routines maintains accuracy even after placing many building blocks. OPAL achieves a 60-nm positional accuracy by optimizing the molecular functionalization and laser power. A two-component structure consisting of 448 1-µm building blocks is assembled, representing the largest number of building blocks used to date in 3D optical tweezer microassembly. Although optical tweezers have previously been used for microfabrication, those results were generally restricted to single-material structures composed of a relatively small number of larger-sized building blocks, with little discussion of critical process parameters. It is anticipated that OPAL will enable the assembly, augmentation, and repair of microstructures composed of specialty micro/nanomaterial building blocks to be used in new photonic, microfluidic, and biomedical devices.

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