. | . |
Physicists detect the enigmatic spin momentum of light by Staff Writers Tokyo, Japan (SPX) Apr 29, 2016
Ever since Kepler's observation in the 17th century that sunlight is one of the reasons that the tails of comets to always face away from the sun, it has been understood that light exerts pressure in the direction it propagates. Radiation pressure is produced by the momentum carried by light, and it plays a crucial role in a variety of systems, from atomic to astronomical scales. In a recent theoretical paper (Extraordinary momentum and spin in evanescent waves Konstantin Y. Bliokh, Aleksandr Y. Bekshaev, Franco Nori Nature Communications, 2014 DOI: 10.1038/ncomms4300), a group from the RIKEN Center for Emergent Matter Science in Japan showed that momentum density in non-uniform optical fields has an unusual component, which is orthogonal to the propagation direction of light and is proportional to the optical spin, which means the degree of circular polarization. They predicted that this spin momentum would produce a transverse spin-dependent optical force, a few orders of magnitude weaker than the usual radiation pressure. Now, based on the theoretical work, a group from RIKEN, the University of Bristol, and other institutions have used an extremely precise technique to experimentally verify that light does in fact exert the extraordinary perpendicular force, which is determined by the polarization of the light. The research has been published in Nature Physics. To measure the new type of optical momentum and force, they used an extremely sensitive nano-cantilever, capable of femtoNewton resolution - meaning it could measure a force even smaller than the force gravity exerts on a single bacterium - which was immersed in an evanescent optical field directly above a total-internal-reflecting glass surface. According to Konstantin Bliokh, the corresponding author of the paper, "Our findings revisit fundamental momentum properties of light and, revealing a new type of optical force, enrich optomechanics." Looking to the future, Franco Nori, who led the research team, says, "Our group's investigations integrate relativistic field-theoretical, quantum-mechanical, and optical aspects of the dynamical properties of light. They offer a new paradigm which could provide insights into a variety of phenomena: from applied optics to high-energy physics."
Related Links RIKEN Stellar Chemistry, The Universe And All Within It
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |