Negative optical force field on supercavitating titanium nitride nanoparticles by a single plane wave

Area of Science:

• Nanophotonics
• Plasmonics
• Optical forces

Background:

• Supercavitating nanoparticles (NPs) exhibit unique light-driven motion.
• These NPs are encapsulated in nanobubbles formed by photo-thermal heating.
• Potential applications include bio-applications, nanofabrication, and nanorobotics.

Purpose of the Study:

• To theoretically investigate the optical force on supercavitating titanium nitride (TiN) NPs.
• To explore conditions that initiate backward motion against the light wave.
• To understand light-matter interactions at the nanoscale.

Main Methods:

• Analysis using vector spherical harmonics to quantify optical force.
• Introduction of optical force vector field lines for motion visualization.
• Characterization of force fields under varied NP and nanobubble sizes and wavelengths.

Main Results:

• Quantified optical forces on supercavitating TiN NPs at near-infrared wavelengths.
• Visualized light-driven motion using optical force vector fields.
• Identified specific optical conditions (NP size, nanobubble size, wavelength) for backward motion.

Conclusions:

• Backward motion of supercavitating TiN NPs is achievable under specific optical conditions.
• This finding opens possibilities for advanced nanorobotic and nanofabrication applications.
• The study provides a framework for controlling nanoscale light-driven motion.