Stability of optical levitation by radiation pressure

Stable optical levitation of transparent hollow dielectric spheres has been demonstrated using TEM01 mode laser beams. The levitation of solid dielectric spheres has been made much more stable using highly convergent TEM00 mode beams. We have discovered the existence of two distinct stable regimes of levitation for solid spheres, one located above the beam focus, the other below it. A particle can be switched back and forth between these regimes. Three separate stable regimes are also possible.