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Friday, November 13, 2009

Stable optical trapping of latex nanoparticles with ultrashort pulsed illumination

Arijit Kumar De, Debjit Roy, Aveek Dutta, and Debabrata Goswami

Here we report how ultrafast pulsed illumination at low average power results in a stable three-dimensional (3D) optical trap holding latex nanoparticles which is otherwise not possible with continuous wave lasers at the same power level. The gigantic peak power of a femtosecond pulse exerts a huge instantaneous gradient force that has been predicted theoretically earlier and implemented for microsecond pulses in a different context by others. In addition, the resulting two-photon fluorescence allows direct observation of trapping events by providing intrinsic 3D resolution.

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