Sagnac Interferometer Enhanced Particle Tracking in Optical Tweezers

TL;DR

This paper proposes a novel setup combining optical tweezers with a Sagnac interferometer to significantly improve the tracking sensitivity of tiny particles, enabling detection of smaller particles with higher precision.

Contribution

The paper introduces a new configuration integrating a Sagnac interferometer with optical tweezers to enhance particle tracking performance.

Findings

Signal-to-noise ratio is increased by a factor of 200 at 99% visibility.

Minimum detectable particle size is reduced by a factor of 2.4.

Enhancement saturates as interferometer visibility approaches 100%.

Abstract

A setup is proposed to enhance tracking of very small particles, by using optical tweezers embedded within a Sagnac interferometer. The achievable signal-to-noise ratio is shown to be enhanced over that for a standard optical tweezers setup. The enhancement factor increases asymptotically as the interferometer visibility approaches 100%, but is capped at a maximum given by the ratio of the trapping field intensity to the detector saturation threshold. For an achievable visibility of 99%, the signal-to-noise ratio is enhanced by a factor of 200, and the minimum trackable particle size is 2.4 times smaller than without the interferometer.