Fano Resonance-Assisted All-Dielectric Array for Enhanced Near-Field Optical Trapping of Nanoparticles

Area of Science:

• Nanophotonics
• Optical Trapping
• Plasmonics

Background:

• Near-field optics offers sub-diffraction limit nanoparticle trapping via optical gradients.
• Achieving stable, efficient trapping without thermal effects remains a challenge.
• Existing dielectric structures provide insufficient trap stiffness.

Purpose of the Study:

• To enhance trap stiffness for efficient nanoparticle trapping.
• To investigate the Fano resonance effect in all-dielectric nanostructures for optical trapping.
• To demonstrate stable, multi-particle trapping capabilities.

Main Methods:

• Utilizing an all-dielectric quadrupole nanostructure.
• Exploiting the Fano resonance effect to enhance optical gradients.
• Characterizing trap stiffness for polystyrene nanoparticles under illumination.

Main Results:

• Achieved a 20-fold enhancement in trap stiffness compared to off-resonance conditions.
• Demonstrated a high effective trap stiffness of 1.19 fN/nm for 100 nm nanoparticles at 4.2 mW/μm² illumination.
• Successfully demonstrated simultaneous trapping of two particles at distinct locations.

Conclusions:

• Fano resonance in dielectric nanostructures significantly enhances optical trap stiffness.
• The developed system enables efficient and stable trapping of nanoparticles without adverse thermal effects.
• The nanostructure design facilitates simultaneous multi-particle trapping, opening avenues for advanced applications.