Media 1: Optical trapping through the localized surface-plasmon resonance of engineered gold nanoblock pairs

Originally published in Optics Express on 29 August 2011 (oe-19-18-17462

Media 3: Optical trapping through the localized surface-plasmon resonance of engineered gold nanoblock pairs

Originally published in Optics Express on 29 August 2011 (oe-19-18-17462

Media 2: Optical trapping through the localized surface-plasmon resonance of engineered gold nanoblock pairs

Originally published in Optics Express on 29 August 2011 (oe-19-18-17462

Media 4: Optical trapping through the localized surface-plasmon resonance of engineered gold nanoblock pairs

Originally published in Optics Express on 29 August 2011 (oe-19-18-17462

Nanostructured Potential of Optical Trapping Using a Plasmonic Nanoblock Pair

We performed two-dimensional mapping of optical trapping potentials experienced by a 100 nm dielectric particle above a plasmon-resonant gold nanoblock pair with a gap of several nanometers. Our results demonstrate that the potentials have nanoscale spatial structures that reflect the near-field landscape of the nanoblock pair. When an incident polarization parallel to the pair axis is rotated by 90°, a single potential well turns into multiple potential wells separated by a distance smaller than the diffraction limit; this is associated with super-resolution optical trapping. In addition, we show that the trap stiffness can be enhanced by approximately 3 orders of magnitude compared to that with conventional far-field trapping

Optical Transport and Sorting of Fluorescent Nanodiamonds inside a Tapered Glass Capillary: Optical Sorting of Nanomaterials at the Femtonewton Scale

Nanoparticles from biological, environmental, or industrial sources always show some dispersion in size, shape, composition, and related physical or chemical properties. Sorting nanoparticles according to well-defined criteria is often a crucial but challenging task. While optical forces may be used to target some specific properties such as the size, shape, absorption wavelength, and chirality of nanoparticles, optical sorting techniques usually suffer from the fast diffusion of nanoparticles in comparison to the relative weakness of the optical forces acting on dielectric nanomaterials in liquid dispersion. To achieve high-efficiency optical sorting of an ensemble of nanoparticles in colloidal dispersion, all the nanoparticles to be sorted should be gathered and kept in the light path for a sufficient time. For this purpose, we investigate the use of tapered glass capillaries as optofluidic platforms for optical manipulation and optical sorting applications. While the transparent pipe-like structure of the capillary serves as an optical waveguide that focuses the laser light over a few-millimeter-long distance, the inner part of the capillary forms a microfluidic channel that is filled with a water dispersion of 100 nm fluorescent nanodiamonds (NDs). We first demonstrate power-dependent optical transport of NDs inside few-micrometer-large capillaries. It is observed that NDs located inside the waist of the tapered capillary can be optically propelled at velocities reaching few tens of micrometer per second. We then show how a liquid flow inside the channel enables efficient, size-dependent sorting of a large ensemble of NDs. An analytical model is used to evaluate the influence of the NDs’ size on the optical and hydrodynamic drag forces acting on the nanoparticles, both being in the femtonewton range

Optical Transport and Sorting of Fluorescent Nanodiamonds inside a Tapered Glass Capillary: Optical Sorting of Nanomaterials at the Femtonewton Scale

Nanoparticles from biological, environmental, or industrial sources always show some dispersion in size, shape, composition, and related physical or chemical properties. Sorting nanoparticles according to well-defined criteria is often a crucial but challenging task. While optical forces may be used to target some specific properties such as the size, shape, absorption wavelength, and chirality of nanoparticles, optical sorting techniques usually suffer from the fast diffusion of nanoparticles in comparison to the relative weakness of the optical forces acting on dielectric nanomaterials in liquid dispersion. To achieve high-efficiency optical sorting of an ensemble of nanoparticles in colloidal dispersion, all the nanoparticles to be sorted should be gathered and kept in the light path for a sufficient time. For this purpose, we investigate the use of tapered glass capillaries as optofluidic platforms for optical manipulation and optical sorting applications. While the transparent pipe-like structure of the capillary serves as an optical waveguide that focuses the laser light over a few-millimeter-long distance, the inner part of the capillary forms a microfluidic channel that is filled with a water dispersion of 100 nm fluorescent nanodiamonds (NDs). We first demonstrate power-dependent optical transport of NDs inside few-micrometer-large capillaries. It is observed that NDs located inside the waist of the tapered capillary can be optically propelled at velocities reaching few tens of micrometer per second. We then show how a liquid flow inside the channel enables efficient, size-dependent sorting of a large ensemble of NDs. An analytical model is used to evaluate the influence of the NDs’ size on the optical and hydrodynamic drag forces acting on the nanoparticles, both being in the femtonewton range

Optical Transport and Sorting of Fluorescent Nanodiamonds inside a Tapered Glass Capillary: Optical Sorting of Nanomaterials at the Femtonewton Scale

Nanoparticles from biological, environmental, or industrial sources always show some dispersion in size, shape, composition, and related physical or chemical properties. Sorting nanoparticles according to well-defined criteria is often a crucial but challenging task. While optical forces may be used to target some specific properties such as the size, shape, absorption wavelength, and chirality of nanoparticles, optical sorting techniques usually suffer from the fast diffusion of nanoparticles in comparison to the relative weakness of the optical forces acting on dielectric nanomaterials in liquid dispersion. To achieve high-efficiency optical sorting of an ensemble of nanoparticles in colloidal dispersion, all the nanoparticles to be sorted should be gathered and kept in the light path for a sufficient time. For this purpose, we investigate the use of tapered glass capillaries as optofluidic platforms for optical manipulation and optical sorting applications. While the transparent pipe-like structure of the capillary serves as an optical waveguide that focuses the laser light over a few-millimeter-long distance, the inner part of the capillary forms a microfluidic channel that is filled with a water dispersion of 100 nm fluorescent nanodiamonds (NDs). We first demonstrate power-dependent optical transport of NDs inside few-micrometer-large capillaries. It is observed that NDs located inside the waist of the tapered capillary can be optically propelled at velocities reaching few tens of micrometer per second. We then show how a liquid flow inside the channel enables efficient, size-dependent sorting of a large ensemble of NDs. An analytical model is used to evaluate the influence of the NDs’ size on the optical and hydrodynamic drag forces acting on the nanoparticles, both being in the femtonewton range

Nanostructured Potential of Optical Trapping Using a Plasmonic Nanoblock Pair

We performed two-dimensional mapping of optical trapping potentials experienced by a 100 nm dielectric particle above a plasmon-resonant gold nanoblock pair with a gap of several nanometers. Our results demonstrate that the potentials have nanoscale spatial structures that reflect the near-field landscape of the nanoblock pair. When an incident polarization parallel to the pair axis is rotated by 90°, a single potential well turns into multiple potential wells separated by a distance smaller than the diffraction limit; this is associated with super-resolution optical trapping. In addition, we show that the trap stiffness can be enhanced by approximately 3 orders of magnitude compared to that with conventional far-field trapping

Chirality enhancement using topology-designed 3D nanophotonic antennas

We explore chiroptical phenomena in 3D chiral nano-gap antennas using topology optimization. The characteristic helical geometries of the topology-designed antennas exhibit giant chiral dissymmetry (g=-1.70) considering the gap intensity, circular-to-linear polarization conversion, and circularly polarized light emission from a linear dipole coupled with the antenna. We observed that the spin angular momentum of light, flowing into the nanogap with opposite signs, locally amplifies optical chirality. These findings carry profound implications for the nanoscale control of complex light-matter interactions with structured light