Hopping and orbiting of Mie-resonant nanoparticles in optical tweezers

Fuente: arXiv
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Auteurs principaux: Toftul, Ivan, Mao, Libang, Balendhran, Sivacarendran, Taha, Mohammad, Kivshar, Yuri, Kruk, Sergey
Format: Preprint
Publié: 2025
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author Toftul, Ivan
Mao, Libang
Balendhran, Sivacarendran
Taha, Mohammad
Kivshar, Yuri
Kruk, Sergey
author_facet Toftul, Ivan
Mao, Libang
Balendhran, Sivacarendran
Taha, Mohammad
Kivshar, Yuri
Kruk, Sergey
contents Optical tweezers have become a powerful tool for measuring parameters of microscale and nanoscale local environments. Motion of particles within optical tweezer traps established itself as a probe for local viscosity, temperature as well as external fields. However, complex motions of trapped particles such as hopping or orbiting conventionally relies on intricate structure of the optical trap, which creates limitations to their applicability, in particular in challenging environments such as living matter. Here we demonstrate experimentally polarization-dependent hopping and orbiting of particles in an optical trap formed by a single Gaussian beam. This novel effect is observed for subwavelength particles with sizes above approximately $λ/3$, where $λ$ is the wavelength of the trapping beam. Our theoretical analysis reveals that the hopping and orbiting arises via the excitation of {\it higher-order Mie resonances}. While smaller particles experiencing dipolar optical forces remain trapped at the beam center, larger particles experience quadrupole optical forces exhibiting more complex behavior. Under linearly polarized illumination, larger particles show {\it bistable dynamics} hopping between two stable positions. Under circularly polarized illumination, trapped particles orbit around the beam center, revealing a light-induced spin-to-orbital angular momentum transfer. Experimental trajectory analysis reveals power-tunable hopping rates and angular velocities. We discuss the effect of VO$_2$ monoclinic-to-rutile phase change on the observed effect. Our results present a robust and reliable way to achieve complex behavior of a particle in simple single-beam tweezers. This should enhance sensitivity of parameter measurements for local environments via optical forces, such as viscosity and temperature inside cells.
format Preprint
id arxiv_https___arxiv_org_abs_2507_10058
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hopping and orbiting of Mie-resonant nanoparticles in optical tweezers
Toftul, Ivan
Mao, Libang
Balendhran, Sivacarendran
Taha, Mohammad
Kivshar, Yuri
Kruk, Sergey
Optics
Optical tweezers have become a powerful tool for measuring parameters of microscale and nanoscale local environments. Motion of particles within optical tweezer traps established itself as a probe for local viscosity, temperature as well as external fields. However, complex motions of trapped particles such as hopping or orbiting conventionally relies on intricate structure of the optical trap, which creates limitations to their applicability, in particular in challenging environments such as living matter. Here we demonstrate experimentally polarization-dependent hopping and orbiting of particles in an optical trap formed by a single Gaussian beam. This novel effect is observed for subwavelength particles with sizes above approximately $λ/3$, where $λ$ is the wavelength of the trapping beam. Our theoretical analysis reveals that the hopping and orbiting arises via the excitation of {\it higher-order Mie resonances}. While smaller particles experiencing dipolar optical forces remain trapped at the beam center, larger particles experience quadrupole optical forces exhibiting more complex behavior. Under linearly polarized illumination, larger particles show {\it bistable dynamics} hopping between two stable positions. Under circularly polarized illumination, trapped particles orbit around the beam center, revealing a light-induced spin-to-orbital angular momentum transfer. Experimental trajectory analysis reveals power-tunable hopping rates and angular velocities. We discuss the effect of VO$_2$ monoclinic-to-rutile phase change on the observed effect. Our results present a robust and reliable way to achieve complex behavior of a particle in simple single-beam tweezers. This should enhance sensitivity of parameter measurements for local environments via optical forces, such as viscosity and temperature inside cells.
title Hopping and orbiting of Mie-resonant nanoparticles in optical tweezers
topic Optics
url https://arxiv.org/abs/2507.10058