Optical trapping of nanoparticles with tunable inter-distance using a multimode slot cavity

Area of Science:

• Nanotechnology
• Optics
• Materials Science
• Photonics

Background:

• Intensive research exists on optical trapping of single nano-objects (nano-tweezers).
• Interactions between multiple trapped nanoparticles have been seldom considered in previous studies.
• Existing nano-tweezers primarily focus on single nanoparticle manipulation.

Purpose of the Study:

• To propose and investigate a novel nano-tweezers system for manipulating multiple nanoparticles.
• To demonstrate control over the relative positions and interactions of two trapped nanoparticles.
• To utilize a slot photonic crystal cavity supporting multiple resonant modes for nanoparticle manipulation.

Main Methods:

• Design of a nano-tweezers system integrated within a slot photonic crystal cavity.
• Selective excitation of different resonant modes (first and second order) within the cavity.
• Observation and analysis of nanoparticle positions and inter-distances based on mode excitation and power tuning.

Main Results:

• Both nanoparticles were trapped at the cavity center when the first-order mode was excited.
• Nanoparticles were stably trapped at two separated positions, repelling each other, when the second-order mode was excited.
• Precise tuning of the inter-particle distance was achieved by adjusting the relative power of the modes.

Conclusions:

• The proposed nano-tweezers system enables optical control over the interactions between two nano-objects.
• Selective excitation of resonant modes in a photonic crystal cavity allows for tunable nanoparticle separation.
• This method offers potential applications in controlling nano-object interactions across various scientific disciplines.