Improvement of optical trapping effect by using the focused high-order Laguerre–Gaussian beams

We investigate the optical trapping effect of high-order Laguerre–Gaussian (LG) beams acting on a dielectric sphere in Rayleigh regime. For LG beams with the azimuthal mode index l = 0, it is found that under the same input power, the transverse trapping effect can be enhanced several times with increasing the radial mode index p, compared with that of the Gaussian beam; while its axial trapping effect is exactly the same as that of Gaussian beam, although the central trapping region reduces as p increases. For LG beams with l ≥ 1, we find that the maximal transverse gradient forces increase with the increasing of p and the axial radiation forces reduces slightly, therefore an optimal choose on p and l is necessary for obtaining an optimal optical guiding. Our result is useful for analyzing the trapping efficiency of LG beams applied in micromanipulation technologies.

► Study radiation forces on Rayleigh particles by using high-order Laguerre–Gaussian (LG) beams. ► Study the effect of both radial and azimuthal mode indexes, p and l, on the trapping efficiency. ► The transverse trapping effect is improved with increasing p, while the axial trapping effect is different for l = 0 and l ≥ 1. ► For the case of l = 0, the larger the value of p, the more efficiency the transverse trapping effect. ► For the case of l ≥ 1, there exists an optimal choose on p and l for a certain application.