Electronic control of optical tweezers using space-time-wavelength mapping

Abstract

We present a new approach for electronic control of optical tweezers by using space--time--wavelength mapping (STWM), a technique that uses time--domain modulation to control local intensity values, and hence the resulting optical force, in space. The proposed technique enables direct control of magnitude, location, and polarity of force hot--spots created by Lorentz force (gradient force). In this paper, we develop an analytical formulation of the proposed STWM technique for optical tweezing. In the case study presented here, we show that 150 fs optical pulses are dispersed in time and space to achieve a focused elliptical beam that is ~20 μm long and ~2 μm wide. By choosing the appropriate RF waveform and electro--optic modulator, we can generate multiple hot--spots with >200 pN force per pulse.

Brownian Motion in Optical Tweezers, a Comparison between MD Simulations and Experimental Data in the Ballistic Regime

“…Now, they are finding applications in many fields of science, such as biology and chemistry, where they are used extensively in studying the unfolding of proteins [ 28 , 29 , 30 ]. Thanks to the advancements in the field electronics, it is now possible to further increase the resolution of optical tweezers in the time domain as well and observe the phenomena that happen on even smaller time scales in the range of ns [ 31 , 32 ]. Therefore, this technique is the best choice to measure the motion of colloidal particles with both time and spatial scales that match those achieved in numerical simulations.…”