Optical Pulling Using Chiral Metalens as a Photonic Probe.

Area of Science:

• Photonics and Nanotechnology
• Optical Manipulation

Background:

• Optical pulling forces can manipulate objects towards the light source.
• Conventional methods using lenses or prisms are too large for microscale manipulation.
• Tailoring electromagnetic fields, environments, or particle properties are current approaches.

Purpose of the Study:

• To design a chiral metalens as a photonic probe for generating optical pulling forces.
• To achieve robust optical pulling forces with a broadband spectrum.
• To investigate the tunability of optical forces via polarization control.

Main Methods:

• Designing and fabricating a chiral metalens.
• Characterizing the induced optical pulling force over a broadband spectrum (1.517–2.117 μm).
• Analyzing the longitudinal optical force response under different circular polarization states.

Main Results:

• A robust optical pulling force was generated by the chiral metalens.
• The force was characterized over a 0.6 μm bandwidth, reaching -83.76 pN/W.
• A circular dichroism response was observed, allowing tunable optical forces from pulling to pushing by controlling polarization.

Conclusions:

• A chiral metalens enables effective optical pulling force generation and manipulation.
• The polarization-dependent response allows flexible control over optical forces.
• This technique has potential applications in contactless fabrication, cell assembly, and spacecraft control.