Single-beam optical gradient force trap apparatus

This invention provides a single-beam optical gradient force trap apparatus which can generate Laguerre-Gaussian laser with exact high-order mode. The apparatus has a high-order Hermite-Gaussian laser generator, and a laser mode converter. The high-order HG laser generator arises a high-order HG01 laser by a concave mirror, a sphere of spherical-cylindrical lens, a aperture and a phase plate between the concave mirror and the spherical-cylindrical lens. The high-order HG01 laser propagates through a cylinder of the spherical-cylindrical lens and transforms a HG01 laser mode and a HG10 laser mode that are equal-ratio, orthogonal and astigmatic. And then, the HG01 laser mode and the HG10 laser mode propagates through a cylinder of a cylindrical lens of the laser mode converter and transforms a LG laser with LG01 laser mode for optical capturing.