Optical tweezers with increased axial trapping efficiency

We demonstrate that the axial trapping efficiency in optical tweezers is improved by using a Laguerre-Gaussian laser mode as the trapping beam. For a wide range of particle sizes and sample cell depths, the laser power required with an l = 3 Laguerre-Gaussian mode is reduced by a factor of two compared with that of the fundamental mode. This is important for biological applications where a reduction in the laser power lessens the risk of damage to living samples.