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1.
ACS Nano ; 2022 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-36053722

RESUMO

Optical manipulation has achieved great success in the fields of biology, micro/nano robotics and physical sciences in the past few decades. To date, the optical manipulation is still witnessing substantial progress powered by the growing accessibility of the complex light field, advanced nanofabrication and developed understandings of light-matter interactions. In this perspective, we highlight recent advancements of optical micro/nanomanipulations in cutting-edge applications, which can be fostered by structured optical forces enabled with diverse auxiliary multiphysical field/forces and structured particles. We conclude with our vision of ongoing and futuristic directions, including heat-avoided and heat-utilized manipulation, nonlinearity-mediated trapping and manipulation, metasurface/two-dimensional material based optical manipulation, as well as interface-based optical manipulation.

2.
Phys Rev Lett ; 129(5): 053902, 2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35960581

RESUMO

Elliptically polarized light waves carry the spin angular momentum (SAM), so they can exert optical torques on nanoparticles. Usually, the rotation follows the same direction as the SAM due to momentum conservation. It is counterintuitive to observe the reversal of optical torque acting on an ordinary dielectric nanoparticle illuminated by an elliptically or circularly polarized light wave. Here, we demonstrate that negative optical torques, which are opposite to the direction of SAM, can ubiquitously emerge when elliptically polarized light waves are impinged on dielectric nanoparticles obliquely. Intriguingly, the rotation can be switched between clockwise and counterclockwise directions by controlling the incident angle of light. Our study suggests a new playground to harness polarization-dependent optical force and torque for advancing optical manipulations.

3.
Nano Lett ; 22(4): 1769-1777, 2022 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-35156826

RESUMO

Circularly polarized light carries spin angular momentum, so it can exert an optical torque on the polarization-anisotropic particle by the spin momentum transfer. Here, we show that giant positive and negative optical torques on Mie-resonant (gain) particles arise from the emergence of superhybrid modes with magnetic multipoles and electric toroidal moments, excited by linearly polarized beams. Anomalous positive and negative torques on particles (doped with judicious amount of dye molecules) are over 800 and 200 times larger than the ordinary lossy counterparts, respectively. Meanwhile, a rotational motor can be configured by switching the s- and p-polarized beams, exhibiting opposite optical torques. These giant and reversed optical torques are unveiled for the first time in the scattering spectrum, paving another avenue toward exploring unprecedented physics of hybrid and superhybrid multipoles in metaoptics and optical manipulations.

4.
Science ; 374(6566): eabj0039, 2021 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-34672745

RESUMO

Rapid progress in miniaturizing vortex devices is driven by their integration with optical sensing, micromanipulation, and optical communications in both classical and quantum realms. Many such efforts are usually associated with on-chip micro- or nanoscale structures in real space and possess a static orbital angular momentum. Recently, a new branch of singular optics has emerged that seeks phase singularities in multiple dimensions, realizing vortex beams with compact nanodevices. Here, we review the topological phase singularities in real space, momentum space, and the spatiotemporal domain for generating vortex beams; discuss recent developments in theoretical and experimental research for generation, detection, and transmission of vortex beams; and provide an outlook for future opportunities in this area, ranging from fundamental research to practical applications.

5.
Opt Lett ; 46(18): 4614-4617, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34525061

RESUMO

Optical trapping of single nanoparticles in vacuum has various applications in both precise measurements and fundamental physics. However, to date, the number and size of randomly loaded nanoparticles in an optical trap is difficult to determine unless in vacuum. In this Letter, an efficient method for nanoparticle size estimation in an optical tweezer system before the evacuation of air was proposed and demonstrated experimentally, using scattering light from levitated particles. The particle radii deduced from the scattering light power in our proposal and from the kinetic theory of particles in gas match well (with the differences of less than 10%). For sample particles with radii ranging within 50-100 nm, we also provide a preselection rule based on this method, where over half of the trapped particles are verified as single particles. Such a particle analysis method is applicable also for the size estimation of levitated diamond particles, gold particles, and other plasmonic particles and can be applied to discovering novel scattering effects.

6.
Nat Commun ; 12(1): 3722, 2021 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-34140523

RESUMO

The ability of light beams to rotate nano-objects has important applications in optical micromachines and biotechnology. However, due to the diffraction limit, it is challenging to rotate nanoparticles at subwavelength scale. Here, we propose a method to obtain controlled fast orbital rotation (i.e., circumgyration) at deep subwavelength scale, based on the nonlinear optical effect rather than sub-diffraction focusing. We experimentally demonstrate rotation of metallic nanoparticles with orbital radius of 71 nm, to our knowledge, the smallest orbital radius obtained by optical trapping thus far. The circumgyration frequency of particles in water can be more than 1 kHz. In addition, we use a femtosecond pulsed Gaussian beam rather than vortex beams in the experiment. Our study provides paradigms for nanoparticle manipulation beyond the diffraction limit, which will not only push toward possible applications in optically driven nanomachines, but also spur more fascinating research in nano-rheology, micro-fluid mechanics and biological applications at the nanoscale.

7.
Opt Express ; 29(7): 11181-11193, 2021 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-33820236

RESUMO

Optical microcavities are capable of confining light to a small volume, which could dramatically enhance the light-matter interactions and hence improve the performances of photonic devices. However, in the previous works on the emergent properties with photonic molecules composed of multiple plasmonic microcavities, the underlying physical mechanism is unresolved, thereby imposing an inevitable restriction on manipulating degenerate modes in microcavity with outstanding performance. Here, we demonstrate the mode-mode interaction mechanism in photonic molecules composed of degenerate-mode cavity and single-mode cavity through utilizing the coupled mode theory. Numerical and analytical results further elucidate that the introduction of direct coupling between the degenerate-mode cavity and single-mode cavity can lift the mode degeneracy and give rise to the mode splitting, which contributes to single Fano resonance and dual EIT-like effects in the double-cavity photonic molecule structure. Four times the optical delay time compared to typical double-cavity photonic molecule are achieved after removing the mode degeneracy. Besides, with the preserved mode degeneracy, ultra-wide filtering bandwidth and high peak transmission is obtained in multiple-cavity photonic molecules. Our results provide a broad range of applications for ultra-compact and multifunction photonic devices in highly integrated optical circuits.

8.
Opt Lett ; 46(1): 106-109, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33362027

RESUMO

Laguerre-Gaussian (LG) beams have orbital angular momentum (OAM). A particle trapped in an LG beam will rotate about the beam axis, due to the transfer of OAM. The rotation of the particle is usually in the same direction as that of the beam OAM. However, we discovered that when the LG beam is strongly focused, the rotation of the particle and the beam OAM might be in the opposite direction. This anomalous effect is caused by the negative torque on the particle exerted by the focused LG beam, which is similar to the optical pulling force in the linear case. We calculated the optical radiation force distribution of a micro-particle trapped in optical tweezers formed by a strongly focused LG beam, and showed that there exist stable trajectories of the particle that are controlled by the negative torque. We propose several necessary conditions for observing the counter-intuitive trajectories. Our work reveals that the strongly trapped micro-particle exhibits diversity of motion patterns.

9.
Opt Lett ; 45(22): 6266-6269, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-33186966

RESUMO

Particles trapped by optical tweezers, behaving as mechanical oscillators in an optomechanical system, have found tremendous applications in various disciplines and are still arousing research interest in frontier and fundamental physics. These optically trapped oscillators provide compact particle confinement and strong oscillator stiffness. But these features are limited by the size of the focused light spot of a laser beam, which is typically restricted by the optical diffraction limit. Here, we propose to build an optical potential well with fine features assisted by the nonlinearity of the particle material, which is independent of the optical diffraction limit. We show that the potential well shape can have super-oscillation-like features and a Fano-resonance-like phenomenon, and the width of the optical trap is far below the diffraction limit. A particle with nonlinearity trapped by an ordinary optical beam provides a new platform with a sub-diffraction potential well and can have applications in high-accuracy optical manipulation and high-precision metrology.

10.
Phys Rev Lett ; 124(22): 223603, 2020 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-32567927

RESUMO

Light has shown an incredible capability in precision measurement based on optomechanic interaction in high vacuum by isolating environment noises. However, there are still obstructions, such as displacement and mass estimation error, highly hampering the improvement of absolute accuracy at the nanoscale. Here, we present a nonlinearity based metrology to precisely measure the position and mass of a nanoparticle with optical levitation under 10^{-5} mbar. By precisely controlling the oscillation amplitude of the levitated nanoparticle at the nonlinear regime for high accuracy calibration, we realized a feasible sub-picometer-level position measurement with an uncertainty of 1.0% without the prior information of mass, which can be further applied to weigh the femtogram-level mass with an uncertainty of 2.2%. It will also pave the way to construct a fine-calibrated optomechanic platform in high vacuum for high sensitivity and accuracy measurement in force and acceleration at the nanoscale and the study in quantum superposition at the mesoscopic scale.

11.
Light Sci Appl ; 7: 86, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30416722

RESUMO

Optical tweezers, crowned by Nobel Prize the first time in 1990s, have widely impacted the research landscape of atom cooling, particle manipulation/sorting, and biology. After more than two decades of steady development, it received the deserving recognition once again in 2018. Unprecedented advancements across various disciplines are believed to be spurred furthermore by this important tool of optical manipulation.

12.
Opt Lett ; 43(22): 5587-5590, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-30439901

RESUMO

Precise detection of surface plasmons is crucial for the research of nanophotonics and quantum optics. In this Letter, we used a single nitrogen vacancy center in diamond as a probe to detect the surface plasmon that was tuned by the thickness of a metallic film. The fluorescence intensity and lifetime of the nitrogen vacancy (NV) center were measured to obtain the information of local light-matter interaction. A nonlinear thickness dependent change of the surface plasmon was observed, with the maximum at the thickness of approximately 30 nm. With optimized thickness of silver film, the fluorescence intensity of a single NV center was enhanced 2.6 times, and the lifetime was reduced by a factor of 3, without affecting the coherence time of the NV spin state. The results proved that this system can quantitatively detect the light-matter interaction at nanoscale, and it provides an approach to enhance the fluorescence intensity of a quantum emitter.

13.
Opt Lett ; 43(19): 4582-4585, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30272688

RESUMO

Displacement detection of a spherical particle in focused laser beams with a quadrant photodetector provides a fast and high precision way to determine the particle location. In contrast to the traditional Gaussian beams, the sensitivity of displacement detection using various doughnut beams is investigated. The sensitivity improvement for large spherical particles along the longitudinal direction is reported. With appropriate vortex charge l of the doughnut beams, they can outperform the Gaussian beam to get more than one order of magnitude higher sensitivity and, thus, have potential applications in various high-precision measurements. By using the levitating doughnut beam to detect the particle displacement, the result will also facilitate the recent proposal of levitating a particle in doughnut beams to suppress the light absorption.

14.
Sci Rep ; 4: 7361, 2014 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-25484234

RESUMO

An unknown quantum state cannot be copied and broadcast freely due to the no-cloning theorem. Approximate cloning schemes have been proposed to achieve the optimal cloning characterized by the maximal fidelity between the original and its copies. Here, from the perspective of quantum Fisher information (QFI), we investigate the distribution of QFI in asymmetric cloning machines which produce two nonidentical copies. As one might expect, improving the QFI of one copy results in decreasing the QFI of the other copy. It is perhaps also unsurprising that asymmetric phase-covariant cloning outperforms universal cloning in distributing QFI since a priori information of the input state has been utilized. However, interesting results appear when we compare the distributabilities of fidelity (which quantifies the full information of quantum states), and QFI (which only captures the information of relevant parameters) in asymmetric cloning machines. Unlike the results of fidelity, where the distributability of symmetric cloning is always optimal for any d-dimensional cloning, we find that any asymmetric cloning outperforms symmetric cloning on the distribution of QFI for d ≤ 18, whereas some but not all asymmetric cloning strategies could be worse than symmetric ones when d > 18.


Assuntos
Modelos Teóricos , Algoritmos
15.
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi ; 23(9): 816-8, 2007 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-17825226

RESUMO

AIM: To determine the frequency of the CD4(+)CD25(nt/hi)CD127(lo) regulatory T lymphocytes from the peripheral blood in the Chinese healthy individuals and provide some useful evidence for clinical research of correlative diseases. METHODS: From the CD4(+)CD25(nt/hi)CD127(lo) regulatory T lymphocytes of peripheral blood in 312 Chinese healthy male and female individuals aged from 8 to 60(five age groups were collected) The expression of transcription factor Foxp3 was detected by triplex immuno fluorescence and the frequency of CD4(+)CD25(nt/hi)CD127(lo) regulatory T lymphocytes was determined by flow cytometry. RESULTS: The frequency of CD4(+)CD25(nt/hi)CD127(lo) regulatory T lymphocytes in Chinese healthy individuals was (6.55+/-0.11)%, and the frequency differed among age groups(P=0.015) and sex groups(P<0.05). CD4(+)CD25(nt/hi)CD127(lo) regulatory T lymphocytes specifically express transcription factor Foxp3. CONCLUSION: The frequency of the CD4(+)CD25(nt/hi)CD127(lo) regulatory T lymphocytes from the peripheral blood in the Chinese healthy individuals has been preliminarily determined which lays the foundation for further clinical research of regulatory T lymphocytes. As a specific cell surface marker, CD25(nt/hi)CD127(lo) can helpful obtain pure CD4(+)CD25(+) regulatory T lymphocytes and suppress the interference of other cells during cell separation.


Assuntos
Asiáticos , Sangue/metabolismo , Antígenos CD4/metabolismo , Saúde , Subunidade alfa de Receptor de Interleucina-2/metabolismo , Subunidade alfa de Receptor de Interleucina-7/metabolismo , Linfócitos T Reguladores/metabolismo , Adolescente , Adulto , Animais , Biomarcadores/metabolismo , Contagem de Linfócito CD4 , Criança , Feminino , Fatores de Transcrição Forkhead/metabolismo , Regulação da Expressão Gênica , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Ratos , Linfócitos T Reguladores/citologia
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