Subwavelength optical trapping with a fiber-based surface plasmonic lens

Area of Science:

• Optics and Photonics
• Biophysics
• Nanotechnology

Background:

• Optical tweezers are crucial tools for manipulating microscopic objects.
• Conventional optical tweezers face limitations in trapping efficiency and proximity to samples.
• Surface plasmon tweezers offer enhanced light-matter interactions but can cause thermal damage.

Purpose of the Study:

• To demonstrate three-dimensional (3D) optical trapping of subwavelength particles and bacteria using a novel fiber-based system.
• To establish the first single fiber optical tweezers capable of 3D trapping.
• To compare the performance of this new system with conventional and surface plasmon tweezers.

Main Methods:

• Fabrication of a surface plasmonic lens on the endface of an optical fiber.
• Utilizing the fiber optic setup for three-dimensional optical trapping experiments.
• Characterization of trapping stability and optical power requirements.
• Comparison of trap distance and thermal effects with existing technologies.

Main Results:

• Successful 3D optical trapping of subwavelength polystyrene beads and bacteria was achieved.
• This represents the first demonstration of 3D trapping using single fiber optical tweezers.
• The system requires lower optical power for stable trapping compared to conventional tweezers, indicating a stronger trap.
• The trap is located approximately 6 wavelengths from the fiber endface, minimizing thermal effects and preventing physical contact.

Conclusions:

• Fiber-based optical tweezers with integrated plasmonic lenses provide an effective platform for 3D particle manipulation.
• This technology offers advantages over conventional and surface plasmon tweezers, including enhanced trap strength and reduced thermal damage.
• The ability to trap at a distance opens new possibilities for studying live biological samples without direct contact or thermal interference.