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Salsabil SH, Dastegir Al-Quaderi G, Mahdy M. Quantum mechanical lateral force on an atom due to matter wave. Heliyon 2024; 10:e23449. [PMID: 38192828 PMCID: PMC10772092 DOI: 10.1016/j.heliyon.2023.e23449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/03/2023] [Accepted: 12/04/2023] [Indexed: 01/10/2024] Open
Abstract
The area of trapping the atoms or molecules using light has advanced tremendously in the last few decades. In contrast, the idea of controlling (not only trapping) the movement of atomic-sized particles using matter waves is a completely new emerging area of particle manipulation. Though a single previous report has suggested the pulling of atoms based on matter-wave tractor beams, an attempt is yet to be made to produce a lateral force using this technique. This article demonstrates an asymmetric setup that engenders reversible lateral force on an atom due to the interaction energy of the matter wave in the presence of a metal surface. Several full-wave simulations and analytical calculations were performed on a particular set-up of Xenon scatterers placed near a Copper surface, with two counter-propagating plane matter waves of Helium impinging in the direction parallel to the surface. By solving the time-independent Schrödinger equation and using the solution, quantum mechanical stress tensor formalism is applied to compute the force acting on the particle. The simulation results are in excellent agreement with the analytical calculations. The results for the adsorbed scatterer case find this technique to be an efficient cleaning procedure similar to electron-stimulated desorption for futuristic applications.
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Affiliation(s)
- Sadia Humaira Salsabil
- Department of Electrical & Computer Engineering, North South University, Bashundhara, Dhaka 1229, Bangladesh
| | | | - M.R.C. Mahdy
- Department of Electrical & Computer Engineering, North South University, Bashundhara, Dhaka 1229, Bangladesh
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2
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Riccardi M, Martin OJF. Electromagnetic Forces and Torques: From Dielectrophoresis to Optical Tweezers. Chem Rev 2023; 123:1680-1711. [PMID: 36719985 PMCID: PMC9951227 DOI: 10.1021/acs.chemrev.2c00576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Indexed: 02/02/2023]
Abstract
Electromagnetic forces and torques enable many key technologies, including optical tweezers or dielectrophoresis. Interestingly, both techniques rely on the same physical process: the interaction of an oscillating electric field with a particle of matter. This work provides a unified framework to understand this interaction both when considering fields oscillating at low frequencies─dielectrophoresis─and high frequencies─optical tweezers. We draw useful parallels between these two techniques, discuss the different and often unstated assumptions they are based upon, and illustrate key applications in the fields of physical and analytical chemistry, biosensing, and colloidal science.
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Affiliation(s)
- Marco Riccardi
- Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), EPFL-STI-NAM, Station 11, CH-1015Lausanne, Switzerland
| | - Olivier J. F. Martin
- Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), EPFL-STI-NAM, Station 11, CH-1015Lausanne, Switzerland
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3
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Cao T, Wang Z, Mao L. Reconfigurable label-free shape-sieving of submicron particles in paired chalcogenide waveguides. NANOSCALE 2022; 14:2465-2474. [PMID: 35103269 DOI: 10.1039/d1nr05798g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Up-to-date particle sieving schemes face formidable challenges for sieving label-free submicron molecules with similar sizes and dielectric constants but diverse shapes. Herein, optical sorting of polystyrene particles with various shapes is illustrated in optofluidic nanophotonic paired waveguide (ONPW) composed of chalcogenide semiconductor Sb2Se3. The Sb2Se3-ONPW creates the coupling length (CL) between the neighboring hot spots that can be actively modulated via the transition of Sb2Se3 between amorphous (AM) and crystalline (CR) phases. Submicron particles interfere with the coupled hotspots, which can exert various optical torques on the particles according to their profiles. In the model system, spherical (diameter of 0.5 μm) and rod-shaped (diameter of 0.5 μm, length of 1.5 μm) polystyrene particles were employed to mimic two types of bacteria, namely, Staphylococcus aureus and rod-shaped Escherichia coli, respectively. For the AM state, the CL value is ∼7.0 μm, enabling the structure to trap the sphere stably in the hot spots. For the CR state, the CL value becomes ∼25 μm, leading to stable trapping of the rod-shaped particle. In this work, the working wavelength was fixed at 1.55 μm at which both AM- and CR-Sb2Se3 are transparent. Our scheme may offer a paradigm shift in shape-selective sieving of biomolecules and fulfill the requirements of the new-generation lab-on-chip techniques, where the integrated manipulation system must be much more multifunctional and flexible.
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Affiliation(s)
- Tun Cao
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, China.
| | - Zhongming Wang
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, China.
| | - Libang Mao
- School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, China.
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4
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Annušová A, Bodík M, Hagara J, Kotlár M, Halahovets Y, Mičušík M, Chlpík J, Cirák J, Hofbauerová M, Jergel M, Majková E, Šiffalovič P. On the extraction of MoO x photothermally active nanoparticles by gel filtration from a byproduct of few-layer MoS 2 exfoliation. NANOTECHNOLOGY 2020; 32:045708. [PMID: 33140739 DOI: 10.1088/1361-6528/abc035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Gel filtration is a versatile technique employed for biological molecules and nanoparticles, offering their reproducible classification based on size and shape. Colloidal nanoparticles are of significant interest in biomedical applications due to a large number of solution-based bioconjugation procedures. Nevertheless, the inherent polydispersity of the nanoparticles produced by various techniques necessitates the employment of high yield separation and purification techniques. Here we demonstrate the employment of gel filtration on non-stoichiometric plasmonic MoO x nanoparticles, prepared by an oxidation process during liquid-phase exfoliation of few-layer MoS2 nanosheets. This resulted in the separation of two types of MoO x particles, in the form of two different chromatographic fractions. They showed different sizes, morphological and optical properties. The fraction containing smaller particles with diameters of 1-4 nm, exhibited an increased absorbance peak in the near IR region and responded with a significant temperature increase to laser irradiation at the wavelength close to the maximal absorption. The fraction with the larger particles from 3 up to 10 nm, showed weak photoluminescence and a preferred orientation upon the deposition on a planar substrate. However, it had no absorbance in the near IR compared to the former fraction. According to our knowledge, this is the first time that the gel filtration was applied to the separation of molybdenum oxide nanomaterials. This step ensured the isolation of plasmonic MoO x nanoparticles suitable for further bioconjugation and target photothermal treatment.
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Affiliation(s)
- Adriana Annušová
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11 Bratislava, Slovakia. Centre for Advanced Material Application, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11 Bratislava, Slovakia
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5
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Xiao F, Zhang J, Yu W, Zhu W, Mei T, Premaratne M, Zhao J. Reversible optical binding force in a plasmonic heterodimer under radially polarized beam illumination. OPTICS EXPRESS 2020; 28:3000-3008. [PMID: 32121976 DOI: 10.1364/oe.380057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 01/01/2020] [Indexed: 06/10/2023]
Abstract
We investigated the optical binding force in a plasmonic heterodimer structure consisting of two nano-disks. It is found that when illuminated by a tightly focused radially polarized beam (RPB), the plasmon modes of the two nano-disks are strongly hybridized, forming bonding/antibonding modes. An interesting observation of this setup is that the direction of the optical binding force can be controlled by changing the wavelength of illumination, the location of the dimer, the diameter of the nano-disks, and the dimer gap size. Further analysis yields that the inhomogeneous polarization state of RPB can be utilized to readily control the bonding type of plasmon modes and distribute the underlying local field confined in the gap (the periphery) of the dimer, leading to a positive (negative) optical binding force. Our findings provide a clear strategy to engineer optical binding forces via changes in device geometry and its illumination profile. Thus, we envision a significant role for our device in emerging nanophotonics structures.
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Zangeneh-Nejad F, Fleury R. Topological Fano Resonances. PHYSICAL REVIEW LETTERS 2019; 122:014301. [PMID: 31012649 DOI: 10.1103/physrevlett.122.014301] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Indexed: 06/09/2023]
Abstract
The Fano resonance is a widespread wave scattering phenomenon associated with a peculiar asymmetric and ultrasharp line shape, which has found applications in a large variety of prominent optical devices. While its substantial sensitivity to geometrical and environmental changes makes it the cornerstone of efficient sensors, it also renders the practical realization of Fano-based systems extremely challenging. Here, we introduce the concept of topological Fano resonance, whose ultrasharp asymmetric line shape is guaranteed by design and protected against geometrical imperfections, yet remaining sensitive to external parameters. We report the experimental observation of such resonances in an acoustic system, and demonstrate their inherent robustness to geometrical disorder. Such topologically protected Fano resonances, which can also be found in microwave, optical, and plasmonic systems, open up exciting frontiers for the generation of various reliable wave-based devices including low-threshold lasers, perfect absorbers, ultrafast switches or modulators, and highly accurate interferometers, by circumventing the performance degradations caused by inadvertent fabrication flaws.
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Affiliation(s)
- Farzad Zangeneh-Nejad
- Laboratory of Wave Engineering, School of Engineering, EPFL, Station 11, 1015 Lausanne, Switzerland
| | - Romain Fleury
- Laboratory of Wave Engineering, School of Engineering, EPFL, Station 11, 1015 Lausanne, Switzerland
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7
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Nan F, Yan Z. Sorting Metal Nanoparticles with Dynamic and Tunable Optical Driven Forces. NANO LETTERS 2018; 18:4500-4505. [PMID: 29939760 DOI: 10.1021/acs.nanolett.8b01672] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Precise sorting of colloidal nanoparticles is a challenging yet necessary task for size-specific applications of nanoparticles in nanophotonics and biochemistry. Here we present a new strategy for all-optical sorting of metal nanoparticles with dynamic and tunable optical driven forces generated by phase gradients of light. Size-dependent optical forces arising from the phase gradients of optical line traps can drive nanoparticles of different sizes with different velocities in solution, leading to their separation along the line traps. By using a sequential combination of optical lines to create differential trapping potentials, we realize precise sorting of silver and gold nanoparticles in the diameter range of 70-150 nm with a resolution down to 10 nm. Separation of the nanoparticles agrees with the analysis of optical forces acting on them and with simulations of their kinetic motions. The results provide new insights into all-optical nanoparticle manipulation and separation and reveal that there is still room to sort smaller nanoparticle with nanometer precision using dynamic phase-gradient forces.
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Affiliation(s)
- Fan Nan
- Department of Chemical and Biomolecular Engineering , Clarkson University , Potsdam , New York 13699 , United States
| | - Zijie Yan
- Department of Chemical and Biomolecular Engineering , Clarkson University , Potsdam , New York 13699 , United States
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8
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Wang H. Plasmonic refractive index sensing using strongly coupled metal nanoantennas: nonlocal limitations. Sci Rep 2018; 8:9589. [PMID: 29941992 PMCID: PMC6018101 DOI: 10.1038/s41598-018-28011-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 06/14/2018] [Indexed: 11/18/2022] Open
Abstract
Localized surface plasmon resonance based on coupled metallic nanoparticles has been extensively studied in the refractive index sensing and the detection of molecules. The amount of resonance peak-shift depends on the refractive index of surrounding medium and the geometry/symmetry of plasmonic oligomers. It has recently been found that as the feature size or the gap distance of plasmonic nanostructures approaches several nanometers, quantum effects can change the plasmon coupling in nanoparticles. However, most of the research on plasmonic sensing has been done based on classical local calculations even for the interparticle gap below ~3 nm, in which the nonlocal screening plays an important role. Here, we theoretically investigate the nonlocal effect on the evolution of various plasmon resonance modes in strongly coupled nanoparticle dimer and trimer antennas with the gap down to 1 nm. Then, the refractive index sensing in these nonlocal systems is evaluated and compared with the results in classical calculations. We find that in the nonlocal regime, both refractive index sensibility factor and figure of merit are actually smaller than their classical counterparts mainly due to the saturation of plasmon shifts. These results would be beneficial for the understanding of interaction between light and nonlocal plasmonic nanostructures and the development of plasmonic devices such as nanosensors and nanoantennas.
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Affiliation(s)
- Hancong Wang
- The Fujian Provincial Key Laboratory of Automotive Electronics and Electric Drive, Research center for Microelectronics Technology, School of Information Science and Engineering, Fujian University of Technology, Fuzhou, 350108, PR China.
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9
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Cao T, Bao J, Mao L. Switching of Giant Lateral Force on Sub-10 nm Particle Using Phase-Change Nanoantenna. ADVANCED THEORY AND SIMULATIONS 2018. [DOI: 10.1002/adts.201700027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Tun Cao
- School of Optoelectronic Engineering and Instrumentation Science; Dalian University of Technology; Dalian 116024 China
| | - Jiaxin Bao
- School of Optoelectronic Engineering and Instrumentation Science; Dalian University of Technology; Dalian 116024 China
| | - Libang Mao
- School of Optoelectronic Engineering and Instrumentation Science; Dalian University of Technology; Dalian 116024 China
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10
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Zheng C, Jia T, Zhao H, Xia Y, Zhang S, Feng D, Sun Z. Theoretical study on narrow Fano resonance of nanocrescent for the label-free detection of single molecules and single nanoparticles. RSC Adv 2018; 8:3381-3391. [PMID: 35542955 PMCID: PMC9077704 DOI: 10.1039/c7ra12666b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/10/2018] [Indexed: 01/29/2023] Open
Abstract
This paper reports a narrow Fano resonance of 3D nanocrescent and its application in the label-free detection of single molecules. The Fano resonance depends not only on the gap size but also on the height. The Fano resonance originates from the interference between the quadrupolar mode supported by the horizontal crescent and the dipolar mode along the nanotip. When the height of 3D nanocrescent is 30 nm, the width of Fano resonance is as narrow as 10 nm. The narrow linewidth is caused by the strong narrow resonant absorption coming from the dipolar mode of nanotip overlapping with the quadrupolar mode of nanocrescent, where the absorption spectra are calculated under a horizontal incident light. The narrow Fano resonance is highly sensitive to a single nanoparticle trapped by the nanocrescent. The wavelength shift increases linearly with the refractive index with the relation of Δλ = 22.10n - 28.80, and increases with the size of trapped nanoparticle following a relation of Δλ = 0.826 × r 1.672. These results indicate that if a protein nanoparticle with radius of 2.5 nm is trapped by the nanocrescent, the shift is as large as 4.03 nm.
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Affiliation(s)
- Chunjie Zheng
- State Key Laboratory of Precision Spectroscopy, East China Normal University Shanghai 200062 P. R. China
| | - Tianqing Jia
- State Key Laboratory of Precision Spectroscopy, East China Normal University Shanghai 200062 P. R. China
| | - Hua Zhao
- State Key Laboratory of Precision Spectroscopy, East China Normal University Shanghai 200062 P. R. China
| | - Yingjie Xia
- State Key Laboratory of Precision Spectroscopy, East China Normal University Shanghai 200062 P. R. China
| | - Shian Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University Shanghai 200062 P. R. China
| | - Donghai Feng
- State Key Laboratory of Precision Spectroscopy, East China Normal University Shanghai 200062 P. R. China
| | - Zhenrong Sun
- State Key Laboratory of Precision Spectroscopy, East China Normal University Shanghai 200062 P. R. China
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11
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Cao T, Qiu Y. Lateral sorting of chiral nanoparticles using Fano-enhanced chiral force in visible region. NANOSCALE 2018; 10:566-574. [PMID: 29182186 DOI: 10.1039/c7nr05464e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Chiral gradient force allows a passive separation of an enantiomer since its direction is dependent on the handedness of its chiral entities. However, chiral polarisability is much weaker than electric polarisability. As a consequence, the non-chiral gradient force dominates over chiral force, which makes enantioselective sorting challenging. We present here, both numerically and analytically, that the chiral gradient force acting on chiral nanoparticles can overcome the non-chiral force when specimens are placed in a Fano-enhanced chiral gradient near-field using a plasmonic nanoaperture. Under circularly polarized light illumination, the interaction between the resonant modes of symmetric outer and asymmetric inner Au split-rings results in a splitting of the modal energies, which excites multipolar interference Fano resonances (FRs). This enables a local aperture between the two split-rings to possess very large optical chirality gradients while maintaining low gradients of electromagnetic energy density around the FRs from the visible region. By way of the lateral resultant force composed of both chiral and non-chiral gradient forces, we can accomplish a helicity-dependent transverse deflection of the chiral nanoparticles positioned above the aperture, which may offer a good platform for all-optical enantiopure compounds.
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Affiliation(s)
- Tun Cao
- Department of Biomedical Engineering, Dalian University of Technology, Dalian 116024, China.
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12
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Bian X, Gao DL, Gao L. Tailoring optical pulling force on gain coated nanoparticles with nonlocal effective medium theory. OPTICS EXPRESS 2017; 25:24566-24578. [PMID: 29041401 DOI: 10.1364/oe.25.024566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/08/2017] [Indexed: 06/07/2023]
Abstract
We study the optical scattering force on the coated nanoparticles with gain core and nonlocal plasmonic shell in the long-wavelength limit, and demonstrate negative optical force acting on the nanoparticles near the symmetric and/or antisymmetric surface plasmon resonances. To understand the optical force behavior, we propose nonlocal effective medium theory to derive the equivalent permittivity for the coated nanoparticles with nonlocality. We show that the imaginary part of the equivalent permittivity is negative near the surface resonant wavelength, resulting in the negative optical force. The introduction of nonlocality may shift the resonant wavelength of the optical force, and strengthen the negative optical force. Two examples of Fano-like resonant scattering in such coated nanoparticles are considered, and Fano resonance-induced negative optical force is found too. Our findings could have some potential applications in plasmonics, nano-optical manipulation, and optical selection.
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Gao D, Ding W, Nieto-Vesperinas M, Ding X, Rahman M, Zhang T, Lim C, Qiu CW. Optical manipulation from the microscale to the nanoscale: fundamentals, advances and prospects. LIGHT, SCIENCE & APPLICATIONS 2017; 6:e17039. [PMID: 30167291 PMCID: PMC6062326 DOI: 10.1038/lsa.2017.39] [Citation(s) in RCA: 166] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 02/28/2017] [Accepted: 03/07/2017] [Indexed: 05/07/2023]
Abstract
Since the invention of optical tweezers, optical manipulation has advanced significantly in scientific areas such as atomic physics, optics and biological science. Especially in the past decade, numerous optical beams and nanoscale devices have been proposed to mechanically act on nanoparticles in increasingly precise, stable and flexible ways. Both the linear and angular momenta of light can be exploited to produce optical tractor beams, tweezers and optical torque from the microscale to the nanoscale. Research on optical forces helps to reveal the nature of light-matter interactions and to resolve the fundamental aspects, which require an appropriate description of momenta and the forces on objects in matter. In this review, starting from basic theories and computational approaches, we highlight the latest optical trapping configurations and their applications in bioscience, as well as recent advances down to the nanoscale. Finally, we discuss the future prospects of nanomanipulation, which has considerable potential applications in a variety of scientific fields and everyday life.
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Affiliation(s)
- Dongliang Gao
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
- College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China
| | - Weiqiang Ding
- Department of Physics, Harbin Institute of Technology, Harbin 150001, China
| | - Manuel Nieto-Vesperinas
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Campus de Cantoblanco, Madrid 28049, Spain
| | - Xumin Ding
- Department of Physics, Harbin Institute of Technology, Harbin 150001, China
| | - Mahdy Rahman
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
- Department of Electrical and Computer Engineering, North South University, Dhaka 1229, Bangladesh
| | - Tianhang Zhang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
| | - ChweeTeck Lim
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
- Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, Shenzhen University, Shenzhen 518060, China
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14
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Jalal MR, Fathollahi S. Computational study of optical force between two nanodistant plasmonic submicrowires. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2017; 34:1139-1145. [PMID: 29036123 DOI: 10.1364/josaa.34.001139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/26/2017] [Indexed: 06/07/2023]
Abstract
In this paper, the optical force between two circular plasmonic wires of submicrometer diameter (0.3 μm) with nanometer surface-to-surface distances (3-30 nm) interacting with radiation of a complex point source (λ≈0.2 μm) is numerically studied. Calculations (which are based on the Müller integral equations and the Maxwell stress tensor) show that an attractive optical force with a number of distinct peaks is created in distances 3-10 nm. However, for plasmonic-dielectric and plasmonic-reflector double-wires, the optical force has no such peaks. Comparisons reveal that the peaks are originated from the excitation of coupled surface plasmon polaritons in the gap region between the plasmonic wires.
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15
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Pulling cylindrical particles using a soft-nonparaxial tractor beam. Sci Rep 2017; 7:652. [PMID: 28381822 PMCID: PMC5429638 DOI: 10.1038/s41598-017-00735-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/02/2017] [Indexed: 11/09/2022] Open
Abstract
In order to pull objects towards the light source a single tractor beam inevitably needs to be strongly nonparaxial. This stringent requirement makes such a tractor beam somewhat hypothetical. Here we reveal that the cylindrical shape of dielectric particles can effectively mitigate the nonparaxiality requirements, reducing the incidence angle of the partial plane waves of the light beam down to 45° and even to 30° for respectively dipole and dipole-quadrupole objects. The optical pulling force attributed to the interaction of magnetic dipole and magnetic quadrupole moments of dielectric cylinders occurs due to the TE rather than TM polarization. Therefore, the polarization state of the incident beam can be utilized as an external control for switching between the pushing and pulling forces. The results have application values towards optical micromanipulation, transportation and sorting of targeted particles.
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16
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Zhai WC, Qiao TZ, Cai DJ, Wang WJ, Chen JD, Chen ZH, Liu SD. Anticrossing double Fano resonances generated in metallic/dielectric hybrid nanostructures using nonradiative anapole modes for enhanced nonlinear optical effects. OPTICS EXPRESS 2016; 24:27858-27869. [PMID: 27906354 DOI: 10.1364/oe.24.027858] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Third-harmonic generation with metallic or dielectric nanoparticles often suffer from, respectively, small modal volumes and weak near-field enhancements. This study propose and demonstrate that a metallic/dielectric hybrid nanostructure composed of a silver double rectangular nanoring and a silicon square nanoplate can be used to overcome these obstacles for enhanced third-harmonic generation. It is shown that the nonradiative anapole mode of the Si plate can be used as a localized source to excite the dark subradiant octupole mode of the Ag ring, and the mode hybridization leads to the formation of an antibonding and a bonding subradiant collective mode, thereby forming anticrossing double Fano resonances. With the strong coupling between individual particles and the effectively suppressed radiative losses of the Fano resonances, several strong hot spots are generated around the Ag ring due to the excitation of the octupole mode, and electromagnetic fields within the Si plate are also strongly amplified, making it possible to confine more incident energy inside the dielectric nanoparticle. Calculation results reveal that the confined energy inside the Si plate and the Ag ring for the hybrid structures can be about, respectively, more than three times and four orders stronger than that of the corresponding isolated nanoparticles, which makes the designed hybrid nanostructure a promising platform for enhanced third-harmonic generation.
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17
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Yang C, Pan D, Tong L, Xu H. Guided transport of nanoparticles by plasmonic nanowires. NANOSCALE 2016; 8:19195-19199. [PMID: 27830859 DOI: 10.1039/c6nr07490a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Herein, we report the optical trapping and directional transport of nanoparticles in an aqueous solution by plasmonic nanowires. A laser illuminated one end of a silver nanowire and excited the localized and propagating surface plasmons. Optical forces were induced by the surface plasmons, which could trap the nanoparticles in an aqueous solution. Interestingly, the trapped nanoparticles moved along the silver nanowires from the trapping site to the excitation spot of the laser. Such movements of nanoparticles were also observed on curved nanowires, in which the trajectories of the particles were explicitly determined by the shape of the nanowires. More importantly, for a V-shaped silver nanowire, the direction of the movement could be modulated by the polarization of the incident laser. The direction of the movement was opposite to the prediction by the scattering force due to the propagation of surface plasmons, and the driving force could involve the thermal convection of local fluid due to a heating effect. Our findings indicate a novel approach to transport nanoparticles by plasmonic waveguides in aqueous solution.
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Affiliation(s)
- Cui Yang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P.R. China
| | - Deng Pan
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P.R. China
| | - Lianming Tong
- Centre for Nanochemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P.R. China.
| | - Hongxing Xu
- School of Physics and Technology, Wuhan University, Wuhan 430072, P.R. China.
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18
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Si D, Feng K, Kitamura K, Liu A, Pan L, Li W, Liu T, Huang Y, Liu X. Plasmon-driven surface catalysis on photochemically deposited-based SERS substrates. APPLIED OPTICS 2016; 55:8468-8471. [PMID: 27828123 DOI: 10.1364/ao.55.008468] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
For the virtues of convenience and repeatability, photochemically deposited nanoparticles (NPs) as ferroelectric-based surface-enhanced Raman scattering (SERS) substrates have great potential in the surface-plasmon-related applications. In this work, the plasmon-driven surface catalysis (PDSC) reaction is investigated on lithium niobate (LiNbO3) film with photochemically deposited Au NPs. The SERS spectra indicate that the performance of PDSC reaction on a substrate with various Au3+ concentrations in photochemical deposition is obviously different. Combining structure characterization and electromagnetic field simulation, this result is mainly attributed to the surface plasmon coupling between Au NPs. Furthermore, the results also point out that the exposure time in photochemical deposition plays an important role in PDSC reactions. Our studies on photochemically deposited Au NP substrates provide strong support and further understanding to the research on PDSC reactions and also to other surface-plasmon-related fields.
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Lu Y, Du G, Chen F, Yang Q, Bian H, Yong J, Hou X. Tunable potential well for plasmonic trapping of metallic particles by bowtie nano-apertures. Sci Rep 2016; 6:32675. [PMID: 27666667 PMCID: PMC5036050 DOI: 10.1038/srep32675] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 07/25/2016] [Indexed: 11/11/2022] Open
Abstract
In this paper, the tunable optical trapping dependence on wavelength of incident beam is theoretically investigated based on numerical simulations. The Monte Carlo method is taken into account for exploring the trapping characteristics such as average deviation and number distribution histogram of nanoparticles. It is revealed that both the width and the depth of potential well for trapping particles can be flexibly adjusted by tuning the wavelength of the incident beam. In addition, incident wavelengths for the deepest potential well and for the strongest stiffness at bottom are separated. These phenomena are explained as the strong plasmon coupling between tweezers and metallic nanoparticles. In addition, required trapping fluence and particles’ distributions show distinctive properties through carefully modifying the incident wavelengths from 1280 nm to 1300 nm. Trapping with lowest laser fluence can be realized with
1280 nm laser and trapping with highest precision can be realized with 1300 nm laser. This work will provide theoretical support for advancing the manipulation of metallic particles and related applications such as single-molecule fluorescence and surface enhanced Raman spectroscopy.
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Affiliation(s)
- Yu Lu
- Department of Electronic Science and Technology, State Key Laboratory for Manufacturing System Engineering and Key Laboratory of Photonics Technology for Information of Shaanxi Province, School of Electronics &Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, PR China
| | - Guangqing Du
- Department of Electronic Science and Technology, State Key Laboratory for Manufacturing System Engineering and Key Laboratory of Photonics Technology for Information of Shaanxi Province, School of Electronics &Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, PR China
| | - Feng Chen
- Department of Electronic Science and Technology, State Key Laboratory for Manufacturing System Engineering and Key Laboratory of Photonics Technology for Information of Shaanxi Province, School of Electronics &Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, PR China
| | - Qing Yang
- School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, 710049, PR China
| | - Hao Bian
- Department of Electronic Science and Technology, State Key Laboratory for Manufacturing System Engineering and Key Laboratory of Photonics Technology for Information of Shaanxi Province, School of Electronics &Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, PR China
| | - Jiale Yong
- Department of Electronic Science and Technology, State Key Laboratory for Manufacturing System Engineering and Key Laboratory of Photonics Technology for Information of Shaanxi Province, School of Electronics &Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, PR China
| | - Xun Hou
- Department of Electronic Science and Technology, State Key Laboratory for Manufacturing System Engineering and Key Laboratory of Photonics Technology for Information of Shaanxi Province, School of Electronics &Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, PR China
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20
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Cao T, Mao L, Gao D, Ding W, Qiu CW. Fano resonant Ge2Sb2Te5 nanoparticles realize switchable lateral optical force. NANOSCALE 2016; 8:5657-5666. [PMID: 26898233 DOI: 10.1039/c5nr08804f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Sophisticated optical micromanipulation of small biomolecules usually relies on complex light, e.g., structured light, highly non-paraxial light, or chiral light. One emerging technique is to employ chiral light to drive the chiral nanoparticle along the direction perpendicular to the propagation of the light, i.e., the lateral optical force. Here, we theoretically study the lateral optical force exerted by a entirely Gaussian beam. For the very first time we demonstrate that the Fano resonances (FRs) of the Ge2Sb2Te5 (GST) phase-change nanoparticles encapsulated with Au shells could enable a conventional Gaussian laser to exert a lateral force on such a dielectric GST nanoparticle, attributed to the strongly asymmetric energy flow around the sphere in the dipole-quadrupole FRs. More interestingly, the direction of this lateral force could be reversible during the state transition (i.e., from amorphous to crystalline). By bonding small biomolecules to the outer surface of the phase-change nanoparticle, the particle behaves as a direction-selective vehicle to transport biomolecules along opposite directions, at pre-assessed states of the Ge2Sb2Te5 core correspondingly. Importantly, the origin of the reversal of the lateral optical force is further unveiled by the optical singularity of the Poynting vector. Our mechanism of tailoring the FRs of phase-change nanoparticles, not just limited to GST, may bring a new twist to optical micromanipulation and biomedical applications.
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Affiliation(s)
- Tun Cao
- Department of Biomedical Engineering, Dalian University of Technology, Dalian 116024, China.
| | - Libang Mao
- Department of Biomedical Engineering, Dalian University of Technology, Dalian 116024, China.
| | - Dongliang Gao
- College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China
| | - Weiqiang Ding
- Department of Physics, Harbin Institute of Technology, Harbin 150001, China
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Republic of Singapore.
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21
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Chen S, Meng LY, Shan HY, Li JF, Qian L, Williams CT, Yang ZL, Tian ZQ. How To Light Special Hot Spots in Multiparticle-Film Configurations. ACS NANO 2016; 10:581-7. [PMID: 26580830 DOI: 10.1021/acsnano.5b05605] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The precise control over the locations of hot spots in a nanostructured ensemble is of great importance in plasmon-enhanced spectroscopy, chemical sensing, and super-resolution optical imaging. However, for multiparticle configurations over metal films that involve localized and propagating surface plasmon modes, the locations of hot spots are difficult to predict due to complex plasmon competition and synergistic effects. In this work, theoretical simulations based on multiparticle-film configurations predict that the locations of hot spots can be efficiently controlled in the particle-particle gaps, the particle-film junctions, or in both, by suppressing or promoting specific plasmonic coupling effects in specific wavelength ranges. These findings offer an avenue to obtain strong Raman signals from molecules situated on single crystal surfaces and simultaneously avoid signal interference from particle-particle gaps.
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Affiliation(s)
- Shu Chen
- Department of Physics, Xiamen University , Xiamen 361005, China
| | - Ling-Yan Meng
- Department of Physics, Xiamen University , Xiamen 361005, China
| | - Hang-Yong Shan
- Department of Physics, Xiamen University , Xiamen 361005, China
| | - Jian-Feng Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China
| | - Lihua Qian
- School of Physics, Huazhong University of Science and Technology , Wuhan, 430074, China
| | - Christopher T Williams
- Department of Chemical Engineering, University of South Carolina , Columbia, South Carolina 29208, United States
| | - Zhi-Lin Yang
- Department of Physics, Xiamen University , Xiamen 361005, China
| | - Zhong-Qun Tian
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China
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22
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Liu SD, Leong ESP, Li GC, Hou Y, Deng J, Teng JH, Ong HC, Lei DY. Polarization-Independent Multiple Fano Resonances in Plasmonic Nonamers for Multimode-Matching Enhanced Multiband Second-Harmonic Generation. ACS NANO 2016; 10:1442-53. [PMID: 26727133 DOI: 10.1021/acsnano.5b06956] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Plasmonic oligomers composed of metallic nanoparticles are one class of the most promising platforms for generating Fano resonances with unprecedented optical properties for enhancing various linear and nonlinear optical processes. For efficient generation of second-harmonic emissions at multiple wavelength bands, it is critical to design a plasmonic oligomer concurrently having multiple Fano resonances spectrally matching the fundamental excitation wavelengths and multiple plasmon resonance modes coinciding with the harmonic wavelengths. Thus far, the realization of such a plasmonic oligomer remains a challenge. This study demonstrates both theoretically and experimentally that a plasmonic nonamer consisting of a gold nanocross surrounded by eight nanorods simultaneously sustains multiple polarization-independent Fano resonances in the near-infrared region and several higher-order plasmon resonances in the visible spectrum. Due to coherent amplification of the nonlinear excitation sources by the Fano resonances and efficient scattering-enhanced outcoupling by the higher-order modes, the second-harmonic emission of the nonamer is significantly increased at multiple spectral bands, and their spectral positions and radiation patterns can be flexibly manipulated by easily tuning the length of the surrounding nanorods in the nonamer. These results provide us with important implications for realizing ultrafast multichannel nonlinear optoelectronic devices.
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Affiliation(s)
| | - Eunice Sok Ping Leong
- Institute of Materials Research and Engineering, A*STAR , 2 Fusionopolis Way, Singapore 138634
| | - Guang-Can Li
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong, China
| | - Yidong Hou
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong, China
| | - Jie Deng
- Institute of Materials Research and Engineering, A*STAR , 2 Fusionopolis Way, Singapore 138634
| | - Jing Hua Teng
- Institute of Materials Research and Engineering, A*STAR , 2 Fusionopolis Way, Singapore 138634
| | - Hock Chun Ong
- Department of Physics, The Chinese University of Hong Kong , Hong Kong, China
| | - Dang Yuan Lei
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong, China
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23
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Liu SD, Qi X, Zhai WC, Chen ZH, Wang WJ, Han JB. Polarization state-based refractive index sensing with plasmonic nanostructures. NANOSCALE 2015; 7:20171-20179. [PMID: 26607673 DOI: 10.1039/c5nr06336a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Spectral-based methods are often used for label-free biosensing. However, practical implementations with plasmonic nanostructures suffer from a broad line width caused by strong radiative and nonradiative losses, and the sensing performance characterized by figure of merit is poor for these spectral-based methods. This study provides a polarization state-based method using plasmonic nanostructures to improve the sensing performance. Instead of the intensity spectrum, the polarization state of the transmitted field is monitored to analyze variations of the surrounding medium. The polarization state of incidence is strongly modified due to the excitation of surface plasmons, and the ellipticity of the transmitted field changes dramatically around plasmon resonances. Sharp resonances with line widths down to sub-nanometer are achieved by plotting the spectra of the reciprocal of ellipticity. Therefore, the sensing performance can be significantly improved, and a theoretical value of the figure of merit exceeding 1700 is achieved by using the polarization state-based sensing approach.
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Affiliation(s)
- Shao-Ding Liu
- Key Lab of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, P. R. China.
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24
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Chen H, Jiang Y, Wang N, Lu W, Liu S, Lin Z. Lateral optical force on paired chiral nanoparticles in linearly polarized plane waves. OPTICS LETTERS 2015; 40:5530-5533. [PMID: 26625043 DOI: 10.1364/ol.40.005530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate that a lateral optical force (LOF) can be induced on paired chiral nanoparticles with opposite handedness under the illumination of a linearly polarized plane wave. The LOFs on both chiral particles are equal and thus can move the pair sideways, with the direction depending on the separation between two particles, as well as the handedness of particle chirality. Analytical theory reveals that the LOF comes largely from the optical potential gradient established by the multiple scattering of light between the paired particles with asymmetric chirality. In addition, it is weakly dependent on the material loss of a particle, a feature of gradient force, while heavily dependent on the magnitude and handedness of particle chirality. The effect is expected to find applications in sorting and separating chiral dimers of different handedness.
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25
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Pan L, Huang Y, Yang Y, Xiong W, Chen G, Su X, Wei H, Wang S, Wen W. Electromagnetic field redistribution induced selective plasmon driven surface catalysis in metal nanowire-film systems. Sci Rep 2015; 5:17223. [PMID: 26601698 PMCID: PMC4658649 DOI: 10.1038/srep17223] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/27/2015] [Indexed: 12/05/2022] Open
Abstract
For the novel interpretation of Raman spectrum from molecule at metal surface, the plasmon driven surface catalysis (PDSC) reactions have become an interesting topic in the research field of surface enhanced Raman scattering (SERS). In this work, the selective PDSC reactions of p,p’-dimercaptoazobenzene (DMAB) produced from para-aminothiophenol (PATP) or 4-nitrobenzenethiol (4NBT) were demonstrated in the Ag nanowires dimer-Au film systems. The different SERS spectra collected at individual part and adjacent part of the same nanowire-film system pointed out the importance of the electromagnetic field redistribution induced by image charge on film in this selective surface catalysis, which was confirmed by the simulated electromagnetic simulated electro- magnetic field distributions. Our result indicated this electromagnetic field redistribution induced selective surface catalysis was largely affected by the polarization and wavelength of incident light but slightly by the difference in diameters between two nanowires. Our work provides a further understanding of PDSC reaction in metal nanostructure and could be a deep support for the researches on surface catalysis and surface analysis.
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Affiliation(s)
- Liang Pan
- Soft Matter and Interdisciplinary Research Center, College of Physics, Chongqing University, Chongqing, 400044, P. R. China
| | - Yingzhou Huang
- Soft Matter and Interdisciplinary Research Center, College of Physics, Chongqing University, Chongqing, 400044, P. R. China
| | - Yanna Yang
- Soft Matter and Interdisciplinary Research Center, College of Physics, Chongqing University, Chongqing, 400044, P. R. China
| | - Wen Xiong
- Department of Applied Physics, College of Physics, Chongqing University, Chongqing, 400044, P.R. China
| | - Guo Chen
- Department of Applied Physics, College of Physics, Chongqing University, Chongqing, 400044, P.R. China
| | - Xun Su
- Department of Applied Physics, College of Physics, Chongqing University, Chongqing, 400044, P.R. China
| | - Hua Wei
- Department of Applied Physics, College of Physics, Chongqing University, Chongqing, 400044, P.R. China
| | - Shuxia Wang
- Department of Applied Physics, College of Physics, Chongqing University, Chongqing, 400044, P.R. China
| | - Weijia Wen
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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26
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Gao D, Gao L, Novitsky A, Chen H, Luk'yanchuk B. Topological effects in anisotropy-induced nano-fano resonance of a cylinder. OPTICS LETTERS 2015; 40:4162-4165. [PMID: 26368737 DOI: 10.1364/ol.40.004162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate that optical Fano resonance can be induced by the anisotropy of a cylinder rather than frequency selection under the resonant condition. A tiny perturbation in anisotropy can result in a giant switch in the principal optic axis near plasmon resonance. Such anisotropy-induced Fano resonance shows fast reversion between forward and backward scattering at the lowest-energy interference. The near and far fields of the particle change dramatically around Fano resonance. The topology of optical singular points and the trajectory of energy flux distinctly reveal the interaction between the incident wave and the localized surface plasmons, which also determine the far-field scattering pattern. The anisotropy-induced Fano resonance and its high sensitivity open new perspectives on light-matter interactions and promise potential applications in biological sensors, optical switches, and optomechanics.
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27
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Zhang L, Dong Z, Wang YM, Liu YJ, Zhang S, Yang JKW, Qiu CW. Dynamically configurable hybridization of plasmon modes in nanoring dimer arrays. NANOSCALE 2015; 7:12018-12022. [PMID: 26109165 DOI: 10.1039/c5nr03094c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present a novel strategy capable of dynamically configuring the plasmon-induced transparency (PIT) effect with a polarization-dependent controllability based on a nanoring dimer array. The controllable coupling strength between the superradiant and subradiant modes is due to the polarization-dependent field distributions. It is shown that this dynamically controlled PIT is realized with a modulation depth as high as 95%, and a linear dependence of the coupling strength on polarization angle is deduced using a coupled-oscillator model. We believe that our results will inspire further exciting achievements that utilize various polarization states of the electromagnetic wave and pave a way towards applications using PIT with dynamic controllability such as slow light, optical nonlinearities and chemical/bio-sensing.
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Affiliation(s)
- Lei Zhang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583.
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28
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Raziman TV, Martin OJF. Internal optical forces in plasmonic nanostructures. OPTICS EXPRESS 2015; 23:20143-20157. [PMID: 26367672 DOI: 10.1364/oe.23.020143] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a computational study of the internal optical forces arising in plasmonic gap antennas, dolmen structures and split rings. We find that very strong internal forces perpendicular to the propagation direction appear in these systems. These internal forces show a rich behaviour with varying wavelength, incident polarisation and geometrical parameters, which we explain in terms of the polarisation charges induced on the structures. Various interesting and anomalous features arise such as lateral force reversal, optical pulling force, and circular polarisation-induced forces and torques along directions symmetry-forbidden for orthogonal linear polarisations. Understanding these effects and mastering internal forces in plasmonic nanostructures will be instrumental in implementing new functionalities in these nanophotonic systems.
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29
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Chen H, Liu S, Zi J, Lin Z. Fano resonance-induced negative optical scattering force on plasmonic nanoparticles. ACS NANO 2015; 9:1926-35. [PMID: 25635617 DOI: 10.1021/nn506835j] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We demonstrate theoretically that Fano resonance can induce a negative optical scattering force acting on plasmonic nanoparticles in the visible light spectrum when an appropriate manipulating laser beam is adopted. Under the illumination of a zeroth-order Bessel beam, the plasmonic nanoparticle at its Fano resonance exhibits a much stronger forward scattering than backward scattering and consequently leads to a net longitudinal backward optical scattering force, termed Fano resonance-induced negative optical scattering force. The extinction spectra obtained based on the Mie theory show that the Fano resonance arises from the interference of simultaneously excited multipoles, which can be either a broad electric dipole mode and a narrow electric quadrupole mode, or a quadrupole and an octupole mode mediated by the broad electric dipole. Such Fano resonance-induced negative optical scattering force is demonstrated to occur for core-shell, homogeneous, and hollow metallic particles and can therefore be expected to be universal for many other nanostructures exhibiting Fano resonance, adding considerably to the flexibility of optical micromanipulation on the plasmonic nanoparticles. More interestingly, the flexible tunability of the Fano resonance by particle morphology opens up the possibility of tailoring the optical scattering force accordingly, offering an additional degree of freedom to optical selection and sorting of plasmonic nanoparticles.
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Affiliation(s)
- Huajin Chen
- State Key Laboratory of Surface Physics (SKLSP) and Department of Physics, Fudan University , Shanghai 200433, China
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30
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Sancho-Parramon J, Jelovina D. Boosting Fano resonances in single layered concentric core-shell particles. NANOSCALE 2014; 6:13555-13564. [PMID: 25269097 DOI: 10.1039/c4nr03879g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Efficient excitation of Fano resonances in plasmonic systems usually requires complex nano-structure geometries and some degree of symmetry breaking. However, a single-layered concentric core-shell particle presents inherent Fano profiles in the scattering spectra when sphere and cavity modes spectrally overlap. Weak hybridization and suitable choice of core and shell materials gives rise to strong electric dipolar Fano resonances in these systems and retardation effects can result in resonances of higher multipolar order or of magnetic type. Furthermore, suitable tailoring of illumination conditions leads to an enhancement of the Fano resonance by quenching of unwanted electromagnetic modes. Overall, it is shown that single layered core-shell particles can act as robust Fano resonators.
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31
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Zhang Z, Zhou B, Huang Y, Liao Z, Li Z, Li S, Wang S, Wen W. Gold crescent nanodisk array for nanoantenna-enhanced sensing in subwavelength areas. APPLIED OPTICS 2014; 53:7236-7240. [PMID: 25402882 DOI: 10.1364/ao.53.007236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Benefitting from the antenna effect and localized surface plasmon resonance (LSPR), a metal nanoparticle with a designed morphology has the amazing ability to confine light energy into the required extremely small volume, whose refractive index largely affects the optical properties of the whole metal nanoparticle. In this work, the optical spectra and near-field distribution of a gold nanocrescent array were investigated both experimentally and theoretically. To find out the LSPR wavelength and the enhancement using different morphologies of sharp tips, the spectra of gold nanocrescent arrays with different waist widths (d) were first measured, which were then confirmed and analyzed using the finite difference time-domain method and the hybridization theory. At last, the LSPR of this array with 100 nm diameter dielectric nanodisks was studied for sensing in subwavelength areas. Our results showed that because of its giant nanoantenna-enhanced electromagnetic field at the two tips, this gold nanocrescent array could be a suitable local senor to sense the variation of a local medium in a subwavelength area.
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32
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Liaw JW, Lo WJ, Kuo MK. Wavelength-dependent longitudinal polarizability of gold nanorod on optical torques. OPTICS EXPRESS 2014; 22:10858-10867. [PMID: 24921785 DOI: 10.1364/oe.22.010858] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This study theoretically investigates the wavelength-dependent longitudinal polarizability of a gold nanorod (GNR) irradiated by a polarized laser beam. The resultant optical torque in terms of the Maxwell stress tensor was analyzed quantitatively using the multiple multipole method. Our results indicate that the real part of the longitudinal polarizability of GNR can be either positive or negative, leading to the parallel or perpendicular modes, respectively. For the parallel and perpendicular modes, the long axis of GNR is rotated to align parallel and perpendicular, respectively, to the polarization direction of the illuminating light. The turning point between these two modes, depending on the aspect ratio (AR) and the size of GNR, nearly coincides with the longitudinal surface plasmon resonance (LSPR). The perpendicular mode ranges from the transverse SPR to LSPR, and the range of the parallel mode is broadband from LSPR to the near infrared regime. Owing to that a larger optical torque and less plasmonic heating are of concern, an efficiency of optical torque is defined to evaluate the performance of different wavelengths. Analysis results indicate that lasers with wavelength in the perpendicular mode are applicable to rotate and align a GNR of a higher AR. For example, the laser of 785 nm (the perpendicular mode) is superior to that of 1064 nm (the parallel mode, off-resonant from LSPR of 955 nm) for rotating a GNR of AR = 4 and radius 20 nm with an orientation of 45° with respect to the laser polarization.
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