Optical trapping of small particles using a 1.3-microm compact InGaAsP diode laser

Area of Science:

• Optics
• Biophysics
• Laser Physics

Background:

• Optical trapping utilizes laser beams to manipulate microscopic particles.
• Near-infrared lasers offer advantages for biological applications due to reduced scattering and absorption.
• Diode lasers provide a compact and potentially cost-effective alternative to traditional trapping lasers.

Purpose of the Study:

• To investigate the feasibility and reliability of noncontact optical trapping using a single-beam gradient force from a near-infrared diode laser.
• To quantitatively measure the trapping force exerted by the diode laser.
• To compare the trapping performance of the diode laser with that of an Argon (Ar) laser.

Main Methods:

• Employed a single-beam gradient force optical trap.
• Utilized a near-infrared InGaAsP diode laser operating at 1.33 micrometers.
• Tested trapping with polystyrene latex spheres, glass spheres, and yeast cells.
• Measured the horizontal trapping force by moving particles vertically to the beam axis and applying Stokes law.

Main Results:

• Successfully demonstrated noncontact optical trapping of polystyrene latex spheres, glass spheres, and yeast cells.
• Confirmed the feasibility and reliability of diode-laser optical trapping.
• Established a linear relationship between the trapping laser power and the measured horizontal trapping force.
• Provided a quantitative comparison of trapping force with that of an Ar laser.

Conclusions:

• Near-infrared diode lasers are suitable for noncontact optical trapping of small particles.
• The trapping force is linearly dependent on the laser power, consistent with theoretical models.
• Diode-laser-based optical trapping offers a viable alternative for various applications, including biophysics.