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Nonlinear accelerated orbiting motions of optical trapped particles through two-photon absorption
Optics Letters
|December 28, 2020
Summary
Optical vortex beams can trap particles, but two-photon absorption (TPA) causes nonlinear acceleration of particle orbital motion with increasing laser power. This acceleration is proportional to the TPA coefficient, enabling new applications.
Area of Science:
- Nonlinear Optics
- Optical Tweezers
- Nanoparticle Characterization
Background:
- Vortex beams carry optical angular momentum (AM) to induce particle orbital motion.
- Particle rotation typically scales linearly with laser power in linear optics.
Purpose of the Study:
- Investigate optical forces and torques on two-photon absorbing (TPA) Rayleigh particles.
- Analyze orbital motion dynamics beyond the linear optics regime.
Main Methods:
- Using a tightly focused femtosecond-pulsed circularly polarized vortex beam.
- Trapping and analyzing Rayleigh particles with TPA.
Main Results:
- Observed nonlinear acceleration in orbital motion for TPA particles.
- Orbital motion acceleration is directly proportional to the TPA coefficient.
- Demonstrated distinct trapping dynamics compared to non-TPA particles.
Conclusions:
- TPA introduces nonlinearities in optical trapping dynamics.
- Results offer potential for characterizing nanoparticle optical nonlinearity.
- Opens avenues for AM manipulation and particle transport in nonlinear regimes.
