Light-induced in-plane Rotation of Microobjects on Microfibers

TL;DR

This paper demonstrates in-plane rotation of a gold nanoplate on a microfiber driven by nanosecond laser pulses, revealing new insights into light-induced actuation in nonliquid environments through experimental and theoretical analysis.

Contribution

It introduces a novel method for rotating microobjects on microfibers using laser pulses, emphasizing the role of optical absorption gradients, advancing understanding in nonliquid light-driven actuation.

Findings

Successful in-plane rotation of gold nanoplates achieved

Identified the importance of optical absorption gradients

Provided combined experimental and theoretical insights

Abstract

The transfer of angular momentum carried by photons into a microobject has been widely exploited to achieve the actuation of the microobject. However, this scheme is fundamentally defective in nonliquid environments as a result of the scale gap between friction forces ($\mu$N) and optical forces (pN). To bypass this challenge, the researchers have recently proposed to take advantage of elastic waves based on opto-thermo-mechanical effects [1-4]. Grounded on this insight, we here demonstrate and characterize the in-plane rotation of a gold nanoplate in its surface contacting with a microfiber, driven by nanosecond laser pulses, which has not been explored before. Furthermore, we examine the underlying physical mechanisms and highlight the essential role of the spatial gradient of optical absorption. The combined experimental and theoretical results offer new insights into the study of the light-induced actuation of the microobjects in nonliquid environments, an emerging field far from being mature in both comprehensive understanding and practical applications.