Unveiling bulk and surface radiation forces in a dielectric liquid

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Precise control of light-matter interactions is crucial for optical manipulation and material characterization.
• The fundamental definition of electromagnetic momentum density in matter remains debated.
• Nanotechnology applications heavily rely on understanding these interactions.

Purpose of the Study:

• To investigate bulk and boundary optical forces in dielectric fluids using focused laser beams.
• To decouple thermal and nonlinear optical effects from radiation forces.
• To elucidate the origin of time-dependent pressure distributions and their link to electromagnetic momentum.

Main Methods:

• Utilized tightly focused pulsed laser beams to probe optical forces.
• Employed a theoretical framework based on Microscopic Ampère force density.
• Analyzed optical signals to differentiate between thermal, nonlinear optical, and radiation force contributions.

Main Results:

• Demonstrated that electrostriction effects are the primary cause of time-dependent pressure distribution in dielectric fluids.
• Quantified the contribution of optical forces to surface displacements at dielectric-air interfaces.
• Provided experimental evidence for the role of optical forces in interfacial phenomena.

Conclusions:

• Electrostriction is identified as the key mechanism behind laser-induced pressure changes in dielectric fluids.
• The study clarifies the role of optical forces in interfacial phenomena, contributing to a better understanding of electromagnetic momentum density.
• Results offer insights into fundamental light-matter interactions relevant to nanotechnology.