Opto-thermoelectric pulling of light-absorbing particles

Linhan Lin,Yaoran Liu,Abhay Kotnala,Xiaolei Peng,Brian A Korgel,Yuebing Zheng,Pavana Siddhartha Kollipara,Taizhi Jiang

doi:10.1038/s41377-020-0271-6

Abstract

Optomechanics arises from the photon momentum and its exchange with low-dimensional objects. It is well known that optical radiation exerts pressure on objects, pushing them along the light path. However, optical pulling of an object against the light path is still a counter-intuitive phenomenon. Herein, we present a general concept of optical pulling—opto-thermoelectric pulling (OTEP)—where the optical heating of a light-absorbing particle using a simple plane wave can pull the particle itself against the light path. This irradiation orientation-directed pulling force imparts self-restoring behaviour to the particles, and three-dimensional (3D) trapping of single particles is achieved at an extremely low optical intensity of 10−2 mW μm−2. Moreover, the OTEP force can overcome the short trapping range of conventional optical tweezers and optically drive the particle flow up to a macroscopic distance. The concept of self-induced opto-thermomechanical coupling is paving the way towards freeform optofluidic technology and lab-on-a-chip devices.

Highlights

A photon carries momentum, which can be transferred to low-dimensional objects to realize optical manipulation
We propose that the heat generated from a lightabsorbing particle exerts a back action on the particle, which dominates the optical force and enables pulling the particle against the direction of light propagation
The underlying working mechanism of the pulling effect arises from the self-induced opto-thermoelectric field, which is determined by the surface temperature gradient instead of the incident photon momentum

Summary

Introduction

A photon carries momentum, which can be transferred to low-dimensional objects to realize optical manipulation. To maintain the conservation of momentum, the key to achieving optical pulling is to engineer the sign of the momentum change Δ *p during the light–matter interaction. Some strategies have been proposed to achieve optical pulling, such as sign reversal of the Poynting vector[3,4], amplification of the forward-to-backward scattering intensity to transfer backward momentum to the objects[5,6,7,8], or the interaction between the object and the self-collimation mode from the photonic crystals[9]. It can be proven that optical pulling based on momentum transfer between an incident plane wave and low-dimensional objects is unachievable

Methods

Results

Conclusion