Transient chaos and Rayleigh particle escape out of a time modulated optical trap

Abstract

We consider Rayleigh particles in a periodically modulated optical trap formed by two counter-propagating Gaussian beams. It is shown that for certain values of parameters the system exhibits transient chaos which manifests itself in particle acceleration and subsequent directional ejection out of the trap. The escape flights are terminated at the distance of hundreds wavelengths from the trap centrum and the particles return to the trap under the action of the Stokes force. The particle escape is shown to be a threshold effect that can be potentially employed for particle sorting.

Figures (9)

• Figure 1: Periodically modulated optical formed by two counter-propagating beams with the same polarization but different intensities.
• Figure 2: Optical forces calculated from Eq \ref{['potential']}. Red lines show the static component of the force, while the shaded areas show the variation of the force per cycle; $q_0=7.958,\ \bar{\omega}=0.342$. (a) $\delta=0.008$, (b) $\delta=0.011$.
• Figure 3: Poincaré sections for Hamiltonian dynamics; $q_0=7.958,\ \bar{\omega}=0.342$. (a) $\delta=0$, $\nu=1.16$; (b) $\delta=0.008$, $\nu=1.59$; (c) $\delta=0.011$, $\nu=1.55$ .
• Figure 4: Poincaré sections for dissipative dynamics; $q_0=7.958,\ \bar{\omega}=0.342$. (a) $\delta=0.01$, $\kappa=0.0034$, $\nu=1.38$ (b) $\delta=0.01$, $\kappa=0.0171$, $\nu=1.01$.
• Figure 5: Poincaré sections for dissipative escape trajectories. The insets show the distance against time; $q_0=7.958,\ \bar{\omega}=0.342$. (a) $\delta=0.014$, $\kappa=0.0034$ (b) $\delta=0.014$, $\kappa=0.0171$.