Figure 1
APS/Alan Stonebraker

Laser pair makes a strong nanotweezer. A proposed new kind of “optical tweezers” traps nanoparticles where two laser beams overlap. (Top) After the first laser beam (green) excites the nanoparticle, a second laser beam (yellow) stimulates deexcitation, with the recoil from photon emission generating an effective pulling force (red). (Bottom) When the first laser is turned off, there is no excitation, and the second laser beam pushes the nanoparticle (red).