抄録
The principle of optical trapping is based on the interaction between optical electric fields and induced
polarizations (gradient force). Here we describe a novel trapping phenomenon that arises from nonlinear
polarization using ultrashort near-infrared laser pulses. A stable trap site is split into two equivalent
positions, in contrast to conventional (linear) optical trapping where the trap site is at the center of the
focus. The trapping behavior with ultrashort pulses is successfully interpreted in terms of the nonlinear
polarization induced on the trapped particles. Nonlinear optical trapping might greatly expand the
potential of optical trapping.
