Experimental research of doughnut, a new kind of laser trap

The experimental method used to form doughnut laser trap through axicons and by extracting high-order diffractive light component is introduced. It is demonstrated qualitatively that doughnut laser trap has higher axial trapping force than Solid laser trap. The centrical horizontal trap stiffness of doughnut laser trap and solid laser trap is measure by the method of image analyzing. The result demonstrates that solid laser trap is more rigid. The escaping force of laser trap, varying corresponding to different laser power, is measured by fluid mechanical method. The result demonstrates that doughnut laser trap has higher escaping force, thus can manipulate particles with more stability. It is indicated that doughnut laser trap brings lower thermal damnification, makes best use of low magnification objective lens, and helps to develop double laser traps.