Stable optical trapping of latex nanoparticles with ultrashort pulsed illumination

Abstract

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.

Femtosecond-Pulsed Plasmonic Nanotweezers

“…al. showed that latex nanoparticles can be stably trapped using a fs -pulsed input at power densities (75 mW/ µ m 2 ) lower than a comparable CW system (285 mW/ µ m 2 )11. Additionally, Jiang et.…”

Towards controlling molecular motions in fluorescence microscopy and optical trapping: a spatiotemporal approach

“…21 Based on the previous theoretical work by Wang and Zhao [75] and experimental work by Amberadkar and Li [76], which discuss the role of instantaneous pulse intensity, we tried to directly trap 100 nm latex (polystyrene) nano-particles with femtosecond pulsed excitation at a low average power [77]. For 100 nm particles, stable trap was observed when the average power was elevated to ~30 mW as shown in Figure 10(a).…”

“…Thus the pulse repetition rate turns out to be a crucial factor for stably trapping Rayleigh particles. Fortunately, the ~13 ns time lag between two consecutive pulses (inverse of 76 MHz) is too short for the already trapped particle to leave the trapping region [77][78][79].…”

“…This is precisely the reason as to why no effect of pulse chirping on trapping efficiency has been reported [81]. A realistic approach will be to calibrate the instantaneous force exerted by a single pulse, which has been hitherto rendered un-achievable although its effect has been realised experimentally [71,[77][78][79]. 22 …”

Destruction of a spherical polystyrene microparticle in pulsed ultraviolet beam for micromanipulation purpose

“…[1][2][3]. A variety of methods for manipulating microparticles using optical traps of different types exists.…”