Experimental Control of Transport and Current Reversals in a Deterministic Optical Rocking Ratchet

TL;DR

This paper demonstrates experimentally how a deterministic optical rocking ratchet can control particle transport, including current reversals and size-dependent directionality, by using asymmetric light patterns and periodic tilting.

Contribution

It introduces an experimental setup for a deterministic optical ratchet with real-time control and size-dependent current reversal capabilities.

Findings

Particles exhibit controllable current directions.

Current reversals depend on rocking force magnitude and period.

Different particle sizes can experience opposite currents.

Abstract

We present an experimental demonstration of a deterministic optical rocking ratchet. A periodic and asymmetric light pattern is created to interact with dielectric microparticles in water, giving rise to a ratchet potential. The sample is moved with respect to the pattern with an unbiased time-periodic rocking function, which tilts the potential in alternating opposite directions. We obtain a current of particles whose direction can be controlled in real time and show that particles of different sizes may experience opposite currents. Moreover, we observed current reversals as a function of the magnitude and period of the rocking force.