3D controlling the bead linking to DNA molecule in a single-beam nonlinear optical tweezers

The approximate expressions describing the redistribution of laser beam and optical forces in Kerr fluid, and the ratio of refractive indexes basing on the optical Kerr effect in fluid are derived. Basing on them, the dynamic of nonlinear bead in the nonlinear fluid is simulated by the finite different Langevin equation in presence of the optical Kerr and self-focused effects. The radial and axial control processes of bead linking to lambda-phage WLC DNA molecule in fluid space are numerically observed by calibration of the laser power under and upper the critical value, respectively. The stable position-laser power characteristics are numerically found out. Based on the results, a sample of single-beam optical tweezers for 3D (axial and radial) control of bead is proposed and discussed.