Theory of Vector Beams for Chirality and Magnetism Detection of Subwavelength Particles

Hanifeh, Mina; Capolino, Filippo

doi:10.1002/9781119662945.ch13

Cited by 2 publications

(8 citation statements)

References 67 publications

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“…Comparing Equation () and () shows that the APB and RPB are electromagnetically dual. When they have the same beam parameters, their fields are related as [ 46 ]

$$E^{\text{APB}} = \left(\eta\right)_{0} H^{\text{RPB}} \left(\right. \frac{V_{\text{A}}}{V_{\text{R}}} \left.\right) \\ E^{\text{RPB}} = - \left(\eta\right)_{0} H^{\text{APB}} \left(\right.

…”

Section: Cylindrical Polarization Basismentioning

confidence: 99%

“…The transverse fields of the ARPB vanish on the beam axis, where the longitudinal fields persist. [15,22,45,46] This spatial separation is shown in Figure 2a,b, which respectively depict the propagation of the magnitude of the transverse E ⊥ ¼ E ρ ρ þ E φ φ and longitudinal E z electric fields of the ARPB.…”

Section: Introductionmentioning

confidence: 99%

“…In this article, we further advance the concept of a chiral ARPB, defined in terms of an arbitrary relative amplitude

\hat{V}

and phase shift ψ between the APB and the RPB, as in refs. [15,45,46,56]. We introduce a concise notation for the APB and the RPB in Section 2.…”

Section: Introductionmentioning

confidence: 99%

“…[44]. We choose to retain the designation of ARPB from previous work [15,22,45,46] because it encapsulates the combination of an APB and an RPB. This composition results in purely longitudinal electric and magnetic fields on the beam axis, which are important to build an on-axis helicity density that stems only from longitudinal field components, i.e., h = h z .…”

Section: Introductionmentioning

confidence: 99%

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The Combination of the Azimuthally and Radially Polarized Beams: Helicity and Momentum Densities, Generation, and Optimal Chiral Light

Herrero‐Parareda,

Capolino

2024

Advanced Photonics Research

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Herein, the optical properties of the azimuthally radially polarized beam (ARPB), a superposition of an azimuthally polarized beam and a radially polarized beam, which can be tuned to exhibit maximum chirality at a given energy density, are investigated. This condition is called “optimal chiral light” since it represents the maximum possible local chirality at a given energy density. The transverse fields of an ARPB dominate in the transverse plane but vanish on the beam axis, where the magnetic and electric fields are purely longitudinal, leading to an optical chirality density and an energy density that stem solely from the longitudinal field components on the beam axis, where the linear and angular momentum densities vanish. The ARPB does not have a phase variation around the beam axis and nonetheless exhibits a power flow around the beam axis that causes a longitudinal orbital momentum density. Herein, a concise notation for the ARPB is introduced and field quantities are provided, especially for the optimally chiral configuration. The ARPB shows promise for precise 1D chirality probing and enantioseparation of chiral particles along the beam axis, relying solely on its longitudinal electric and magnetic fields. Herein, a setup is provided to generate ARPBs with controlled chirality and orbital angular momentum.

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“…Comparing Equation () and () shows that the APB and RPB are electromagnetically dual. When they have the same beam parameters, their fields are related as [ 46 ]

$$E^{\text{APB}} = \left(\eta\right)_{0} H^{\text{RPB}} \left(\right. \frac{V_{\text{A}}}{V_{\text{R}}} \left.\right) \\ E^{\text{RPB}} = - \left(\eta\right)_{0} H^{\text{APB}} \left(\right.

…”

Section: Cylindrical Polarization Basismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In this article, we further advance the concept of a chiral ARPB, defined in terms of an arbitrary relative amplitude

\hat{V}

and phase shift ψ between the APB and the RPB, as in refs. [15,45,46,56]. We introduce a concise notation for the APB and the RPB in Section 2.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Combination of the Azimuthally and Radially Polarized Beams: Helicity and Momentum Densities, Generation, and Optimal Chiral Light

Herrero‐Parareda,

Capolino

2024

Advanced Photonics Research

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“…For example, CPL only has chirality in the transverse plane, while the ARPB has a purely longitudinal chirality on the beam axis. 17 While a beam with transverse chirality can only reveal the transverse chirality of the sample, which could be mistaken with its anisotropy as the sample is probed in two directions (x and y), 8,18 a beam with just longitudinal chirality only probes the sample along one direction (z). Indeed, one can construct an optical trap by superposing two counter-propagating optimally chiral ARPBs (OC-ARPBs) of opposite chirality, as depicted in Figure 1.…”

Section: Structured Chiroptical Trappingmentioning

confidence: 99%

Optimally chiral optical trapping

Herrero Parareda,

Capolino

2023

Optical Trapping and Optical Micromanipulation XX

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Our investigation focuses on studying the forces induced on a chiral dipolar particle when exposed to optimally chiral light (OCL). The concept of OCL encompasses all structured light fields that achieve maximum helicity density at a given energy density. Examples of OCL include circularly polarized light (CPL) and the optimally chiral configurations of the azimuthally-radially polarized beam (ARPB), which is a phase-shifted superposition of an azimuthally and a radially polarized beams. The optimal chirality condition requires that light's magnetic and electric fields along the same direction be phase-shifted by a quarter of a period and that the ratio of their magnitudes equals the characteristic impedance in free space [Hanifeh, Albooyeh, Capolino, ACS Phot 2020, 7, 10, 2682-2691. By meeting these conditions, the resulting field also exhibits electric-magnetic symmetry in its energy and spin densities. Consequently, OCL simplifies the computation of forces induced on a chiral dipolar particle, while simultaneously boosting its ability to discern chirality. Notably, the gradient force depends exclusively on the gradient of the energy density (as opposed to a combination of gradients), whereas the remaining forces can be expressed using the Poynting vector and the field's orbital momentum. Given these properties, optimally chiral fields represent a promising avenue for the precise manipulation of chiral nanoparticles. Additionally, the choice of the beam is dependent on the geometry of the optical trap, as different optimally chiral fields have different spatial features. While a beam with CPL induces more pronounced transverse forces that discriminate chirality perpendicular to the propagation direction, the optimally chiral ARPB produces strong longitudinal forces that discriminate chirality along the propagation direction, eliminating the problem of false chirality detection due to electric anisotropy of the nanoparticle.

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Theory of Vector Beams for Chirality and Magnetism Detection of Subwavelength Particles

Cited by 2 publications

References 67 publications

The Combination of the Azimuthally and Radially Polarized Beams: Helicity and Momentum Densities, Generation, and Optimal Chiral Light

The Combination of the Azimuthally and Radially Polarized Beams: Helicity and Momentum Densities, Generation, and Optimal Chiral Light

Optimally chiral optical trapping

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