Focused plasmonic trapping of metallic particles

Min, Changjun; Shen, Zhe; Shen, Jian; Zhang, Yuquan; Fang, Hui; Yuan, Guanghui; Du, Luping; Zhu, Siwei; Lei, Ting; Yuan, Xiaocong

doi:10.1038/ncomms3891

Cited by 363 publications

(246 citation statements)

References 37 publications

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“…optical forces | colloids | microparticles | evanescent field | elliptical motion R ecently, much work has gone into the investigation of optical forces on micro-and nanoparticles near surfaces, primarily in the context of an electric field localized by a microstructured surface (1)(2)(3)(4)(5).…”

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confidence: 99%

Elliptical orbits of microspheres in an evanescent field

Liu

Kheifets

Ginis

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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We examine the motion of periodically driven and optically tweezed microspheres in fluid and find a rich variety of dynamic regimes. We demonstrate, in experiment and in theory, that mean particle motion in 2D is rarely parallel to the direction of the applied force and can even exhibit elliptical orbits with nonzero orbital angular momentum. The behavior is unique in that it depends neither on the nature of the microparticles nor that of the excitation; rather, angular momentum is introduced by the particle's interaction with the anisotropic fluid and optical trap environment. Overall, we find this motion to be highly tunable and predictable.optical forces | colloids | microparticles | evanescent field | elliptical motion R ecently, much work has gone into the investigation of optical forces on micro-and nanoparticles near surfaces, primarily in the context of an electric field localized by a microstructured surface (1-5).Surface-based geometries have raised theoretical excitement due to, for instance, their ability to significantly enhance optical forces (6-8) as well as the emergence of lateral forces due to the extraordinary momentum and spin in evanescent waves (9)(10)(11)(12). From an applied point of view, such geometries can enable miniaturization and parallelization of efficient optical traps enabling integration into optofluidic devices (13,14). Moreover, light-controlled microspheres near surfaces have found applications as force transducers (15-18) and pumps and switches (19,20), and in general, their collective manipulation is an advancing field (21-23).However, in the case where a microparticle is within several diameters of a surface, optical and hydrodynamic surface effects cannot be neglected. Effects arising from optical coupling or reflections can complicate trapping and detection schemes (24), and hydrodynamic interactions can cause the motion of a microparticle to become highly nontrivial (25). Despite this, little quantitative study has been done on the dynamics of optically driven particles near a surface. In studies introducing new schemes to optically manipulate matter, the particle's response function is often ignored (11,12,(26)(27)(28)(29).In this work, we investigate the dynamics of a system with both near field optical forces and surface-induced hydrodynamic effects (see Fig. 1). By driving the particle with an oscillating force from a modulated evanescent field and tracking the particle's motion closely in two dimensions, we map out a range of dynamics that can arise from the interplay of optical and hydrodynamic surface effects. We find that the magnitude and direction of the optical force depends on particle size. We also observe that the trajectory of the particle in general does not follow the direction of the force. Instead, the shape and the orientation of the trajectory vary with modulation frequency and distance of the particle from the surface, a result of the anisotropy in both the hydrodynamic drag and the optical trap spring constant.In particular, we find that under ce...

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confidence: 99%

Elliptical orbits of microspheres in an evanescent field

Liu

Kheifets

Ginis

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…[1][2][3][4] According to the spatial distribution of the polarization, CVBs are classified as radially polarized, azimuthally polarized, and hybridly polarized beams. Particularly, radially polarized beams can be focused into tighter focal spots with a strong longitudinal field component 5 and were applied in high-resolution imaging, 6 nanoparticle manipulation, 7 material processing, 8 plasmonic focusing, 9 and Z-scan technique, 10 etc. Various techniques have been developed to generate CVBs or vortex beams, such as axial birefringent components, spatial light modulators, angular gratings, and interferometric methods.…”

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confidence: 99%

Ultrafast all-fiber based cylindrical-vector beam laser

Mao

Feng

Zhang

et al. 2017

Applied Physics Letters

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Cylindrical-vector beams (CVBs) with axial symmetry in polarization and field intensity are gathering increasing attention from fundamental research to practical applications. However, a majority of the CVBs are generated by modulating light beams in free space, and the temporal durations are far away from the ultrafast regime. Here, an ultrafast all-fiber based CVB laser is demonstrated via intermodal coupling in two mode fibers. In the temporal domain, chirp-free pulses are formed with combined actions of the ultrafast saturable absorption, self-phase modulation, and anomalous dispersion. In the spatial domain, the lateral offset splicing technique and a two mode fiber Bragg grating are adopted to excite and extract CVBs, respectively. The ultrafast CVB has an annular profile with a duration of 6.87 ps and a fundamental repetition rate of 13.16 MHz, and the output polarization status is switchable between radially and azimuthally polarized states. This all-fiber-based ultrafast CVB laser is a simple, low-cost source for diversified applications of nanoparticle manipulation, high-resolution imaging, material processing, spatiotemporal nonlinear optics, etc.

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“…Therefore, we can easily control the number of hot spots of SPPs by simply choosing the desired incident polarization mode, which could contribute to trap desired number of particles in plasmonic tweezers. 17 To summarize, we have introduced space-variant locally linear SOP of the incident vector beam to manipulate SPPs excited in a high NA microscopic configuration. Based on the vector diffraction theory, we build an analytical model for the three-dimensional electric field of SPPs excited by the vector beams.…”

mentioning

confidence: 99%

“…1,2 Moreover, in our recent work, this sharp SPPs field has proved to own unique capabilities in trapping metallic particles. 17 While an azimuthally polarized (AP) beam is unable to excite SPPs due to the polarization mismatch. 13 In recent years, apart from the well-known RP and AP beams, a lot of other vector beams with various space-variant state of polarization (SOP) have been reported, [18][19][20][21][22][23][24][25] for instance, vector beams with cylindrical, [18][19][20] elliptical, 21 and bipolar symmetries 22 of linear polarization.…”

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confidence: 99%

Dynamic plasmonic beam shaping by vector beams with arbitrary locally linear polarization states

Man

Min

et al. 2014

Applied Physics Letters

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Vector beams, which have space-variant state of polarization (SOP) comparing with scalar beams with spatially homogeneous SOP, are used to manipulate surface plasmon polarizations (SPPs). We find that the excitation, orientation, and distribution of the focused SPPs excited in a high numerical aperture microscopic configuration highly depend on the space-variant polarization of the incident vector beam. When it comes to vector beam with axial symmetry, multi-foci of SPPs with the same size and uniform intensity can be obtained, and the number of foci is depending on the polarization order n. Those properties can be of great value in biological sensor and plasmonic tweezers applications. Surface plasmon polaritons (SPPs) are electromagnetic evanescent waves bound to a metal/dielectric interface. Their properties of strong resonance and enhancement of electromagnetic field make the SPPs attractive in various applications including sensing, 1,2 optoelectronics, 3 superresolution imaging, 4 and negative refraction. 5 Thus, excitation and manipulation of SPPs have attracted significant interest and many novel setups for the generation of SPPs have been proposed so far, such as Kretschmann-Raether 6 and Otto configurations, 7 gratings and defects. [8][9][10] Recently, the method of SPPs excitation based on a high numerical aperture (NA) microscope has drawn an increasing attention due to the highly dynamic and structureless features. [11][12][13][14][15] For example, a tightly focused radially polarized (RP) beam can excite a sharp SPPs peak on a flat metal film, 12 which has a sub-diffraction limit spot size, and thus is well suited for super-resolved imaging 16 and bio-sensing. 1,2 Moreover, in our recent work, this sharp SPPs field has proved to own unique capabilities in trapping metallic particles. 17 While an azimuthally polarized (AP) beam is unable to excite SPPs due to the polarization mismatch. 13 In recent years, apart from the well-known RP and AP beams, a lot of other vector beams with various space-variant state of polarization (SOP) have been reported, 18-25 for instance, vector beams with cylindrical, 18-20 elliptical, 21 and bipolar symmetries 22 of linear polarization. The geometric configuration of linear polarizations as an additional degree of freedom should be considered in terms of SPPs manipulation, and consequently, produces more novel phenomena with great potentials to new applications.In this Letter, we explore the excitation and manipulation of a focused SPPs field by modulating the polarization mode of incident vector beams. Based on the vectorial diffraction theory, we first build an analytical model for calculating the three-dimensional electric fields of SPPs excited by vector beams with arbitrary locally linear SOP. The cylindrical vector beams with various orders are taken as examples to verify the validity of our analytical model. The theoretical and experimental results reveal that the polarization mode of the incident beam plays an important role in determining the excitation, orie...

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Focused plasmonic trapping of metallic particles

Cited by 363 publications

References 37 publications

Elliptical orbits of microspheres in an evanescent field

Elliptical orbits of microspheres in an evanescent field

Ultrafast all-fiber based cylindrical-vector beam laser

Dynamic plasmonic beam shaping by vector beams with arbitrary locally linear polarization states

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