Optical trapping and manipulating with a transmissive and polarization-insensitive metalens

Area of Science:

• Optics and Photonics
• Nanotechnology
• Biophysics

Background:

• Conventional optical tweezers use bulky microscope objectives.
• Metalenses offer a miniaturized, integrated solution for optical manipulation.
• Flat optics enable seamless integration into sample chambers.

Purpose of the Study:

• To develop and demonstrate a transmissive, polarization-insensitive water-immersion metalens.
• To achieve high numerical aperture and focusing efficiency for optical trapping.
• To evaluate the metalens performance in micro-object manipulation and force measurement.

Main Methods:

• Fabrication of a metalens using adaptive nano-antennas.
• Characterization of the metalens numerical aperture (1.28) and focusing efficiency (~50% at 532 nm).
• Demonstration of stable optical trapping and bead steering experiments.

Main Results:

• Achieved lateral trapping stiffness > 500 pN/(μm W), comparable to conventional objectives.
• Demonstrated a lateral manipulation range > 2 μm with stable stiffness over 0.5 μm.
• Metalens performance surpasses previous flat lens designs.

Conclusions:

• The developed metalens enables high-performance, flat-optics-based optical tweezers.
• This technology simplifies and enhances optical trapping and manipulation.
• It is compatible with single-molecule and single-cell experiments, offering ease of use and reliability.