Trapping efficiency of a femtosecond laser and damage thresholds for biological cells

Microparticles including biological cells, are trapped and manipulated using continuous wave (CW) and femtosecond laser tweezers. Although the difference in the optical trapping efficiencies of the CW laser tweezers and the femtosecond laser tweezers is not very large, the difference increases as the particle size decreases perhaps because of potential self-focusing of the femtosecond pulses. In addition, white damage spots are generated near the focus during the femtosecond laser trapping of biological cells even at extremely low average powers. The instantaneous optical damage thresholds were measured as a function of trap depth. These results may be useful in optimizing the optical trapping of biological cells when using femtosecond lasers.