Thermally limited force microscopy on optically trapped single metallic nanoparticles

Abstract

We propose and evaluate a new type of optical force microscope based on a standing wave optical trap. Our microscope, calibrated in-situ and operating in a dynamic mode, is able to trap, without heating, a single metallic nanoparticle of 150 nm that acts as a highly sensitive probe for external radiation pressure. An Allan deviation-based stability analysis of the setup yields an optimal 0.1 Hz measurement bandwidth over which the microscope is thermally limited. Over this bandwidth, and with a genuine sine-wave external drive, we demonstrate an optical force resolution down to 3 fN in water at room temperature with a dynamical range for force detection that covers almost 2 orders of magnitude. This resolution is reached both in the confined and freely diffusing regimes of the optical trap. In the latter, we measure $10^{-11}$ m induced displacements on the trapped nanoparticle, spatially confined within less than 25 nm along the optical axis.

10 pages, 8 figures

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Cited by in corpus (6)

• Probing the screening of the Casimir interaction with optical tweezers
• Optimal protocols and universal time-energy bound in Brownian thermodynamics
• Noise and ergodic properties of Brownian motion in an optical tweezer: looking at the crossover between Wiener and Ornstein-Uhlenbeck processes
• Harvesting information to control non-equilibrium states of active matter
• Subfemtonewton force fields measured with ergodic Brownian ensembles
• Weighing an optically trapped microsphere in thermal equilibrium with air