# Germanium microparticles as optically induced oscillators in optical tweezers

## TL;DR

This paper demonstrates that Germanium microparticles can act as optically induced oscillators in optical tweezers, driven by a balance of optical and thermal forces, with controllable oscillation direction via light polarization.

## Contribution

It introduces Germanium beads as a new type of optically induced oscillator and provides a detailed model of the forces involved, advancing optical manipulation techniques.

## Key findings

- Germanium beads exhibit stable oscillations under focused laser light.
- Oscillation direction can be controlled by light polarization.
- The proposed force model matches experimental observations.

## Abstract

Oscillatory dynamics is a key tool in optical tweezers applications. It is usually implemented by mechanical interventions that cannot be optically controlled. In this work we show that Germanium semiconductor beads behave as optically induced oscillators when subjected to a highly focused laser beam. Such unusual motion is due to the competition between the usual optical forces [1-3] and the radiometric force related to thermal effects, which pushes the beads from the focal region [4]. We characterize the behavior of the Germanium beads in detail and propose a model accounting for the related forces, in good agreement with the experimental data. The well defined direction of oscillations can be manipulated by the polarization of the light beam. Such kind of system can potentially revolutionize the field of optical manipulation, contributing to the design of single molecule machines and the application of oscillatory forces in macromolecules and other soft matter systems.