Mode division multiplexing technology for single-fiber optical trapping axial-position adjustment

Area of Science:

• Biophysics
• Optical Tweezers
• Microfluidics

Background:

• Single-fiber optical trapping systems offer miniaturized solutions for manipulating microscopic particles.
• Traditional optical tweezers require mechanical movement of the fiber to adjust trapping positions, limiting dynamic control.
• Utilizing multimode beams within a single fiber presents an opportunity for novel manipulation techniques.

Purpose of the Study:

• To demonstrate axial-position adjustment of trapped yeast cells without physically moving the optical fiber.
• To explore the use of multimode beams (LP01 and LP11) in a single fiber for dynamic optical trapping control.
• To establish a new method for precise manipulation in single-fiber optical tweezers for potential biomedical applications.

Main Methods:

• Employed a single-fiber optical trapping system utilizing a normal single-core fiber.
• Generated and controlled the power ratio of the fundamental mode beam (LP01) and the low-order mode beam (LP11).
• Fabricated a specialized fiber tapered tip using a selective two-step method to separate trapping positions of the two modes.

Main Results:

• Successfully achieved dynamic axial-position adjustment of a 6 μm diameter yeast cell.
• Demonstrated movement of the yeast cell along the optical axis by approximately 3 μm without fiber movement.
• Confirmed the feasibility of controlling trapping positions by manipulating the power ratio of LP01 and LP11 modes.

Conclusions:

• This study presents the first demonstration of trapping position adjustment without moving the fiber in single-fiber optical tweezers.
• The excitation and utilization of multimode beams in a single fiber represent a significant advancement in optical trapping technology.
• This technique holds promise for more practical and versatile applications in various biomedical research fields.