Giant resonant light forces in microspherical photonics


Resonant light pressure effects can open new degrees of freedom in optical manipulation with microparticles, but they have been traditionally considered as relatively subtle effects. Using a simplified two-dimensional model of surface electromagnetic waves evanescently coupled to whispering gallery modes (WGMs) in transparent circular cavities, we show that under resonant conditions the peaks of the optical forces can approach theoretical limits imposed by the momentum conservation law on totally absorbing particles. Experimentally, we proved the existence of strong peaks of the optical forces by studying the optical propulsion of dielectric microspheres along tapered microfibers. We observed giant optical propelling velocities ∼0.45 mm s−1 for some of the 15-20 µm polystyrene microspheres in water for guided powers limited at ∼43 mW. Such velocities exceed previous observations by more than an order of magnitude, thereby providing evidence for the strongly enhanced resonant optical forces. We analyzed the statistical properties of the velocity distribution function measured for slightly disordered (∼1% size variations) ensembles of microspheres with mean diameters varying from 3 to 20 µm. These results demonstrate a principal possibility of optical sorting of microspheres with the positions of WGM resonances overlapped at the wavelength of the laser source. They can be used as building blocks of the lossless coupled resonator optical waveguides and various integrated optoelectronics devices.

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Divisions: College of Engineering & Physical Sciences > Aston Institute of Photonics Technology (AIPT)
Additional Information: This work is licensed under the Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 Unported License. To view a copy of this license, visit
Publication ISSN: 2047-7538
Last Modified: 04 Jun 2024 07:22
Date Deposited: 02 Feb 2021 14:28
Full Text Link: http://gateway. ... 000324467600002
Related URLs: https://www.nat ... icles/lsa201320 (Publisher URL)
PURE Output Type: Article
Published Date: 2013-04-26
Authors: Li, Yangcheng
Svitelskiy, Oleksiy V.
Maslov, Alexey V.
Carnegie, David
Rafailov, Edik (ORCID Profile 0000-0002-4152-0120)
Astratov, Vasily N.

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