When light falls on an object, it normally is pushed away. This is why, for instance, the dusty tails of comets are bent outward from the sun.<\/p>\n
But demonstrating the idea of using light to attract an object has long been an unattainable goal of scientists \u2013 until now.<\/p>\n
A team of researchers from the Â鶹ӳ»´«Ã½ and the National University of Singapore have shown that it is possible to pull microscopically small objects floating on a water surface in the opposite direction of the illuminating beam. Their study \u201cLinear Momentum Increase and Negative Optical Forces at Dielectric Interface\u201d was published this past weekend on the website of Nature Photonics, a peer-reviewed scientific journal.<\/p>\n
\u201cBecause this new way to generate optically induced action is simple to implement and robust, it opens new avenues in biophotonic sensing and optical manipulation,\u201d said Aristide Dogariu, professor of optics in the Â鶹ӳ»´«Ã½ College of Optics & Photonics. \u201cFor instance, these new types of forces can drive microflows without moving parts or any other additional mechanical or chemical preparations.\u201d<\/p>\n
In their research, the team discovered that forces acting against the flow of light can occur because of the natural amplification of momentum when light passes from one medium into another with a higher light-refractive index.<\/p>\n
The pulling effect occurs, for example, when light travels from air into water. The scattering of the light causes \u201cmomentum conservation\u201d resulting in the negative force that pulls the object backwards.<\/p>\n
\u201cThis is an experimental demonstration of a new concept to achieve so-called \u2018tractor beams.\u2019 Particles can move indefinitely without having to continuously modify the light beam,\u201d Dogariu said.<\/p>\n
Common to many living systems, the environment and chemically engineered products, complex interfaces are created when active molecules or particles collect at the boundaries. \u201cThe flexibility of applying spatially distributed optical forces could lead to new means for macroscopic manipulation of such structures,\u201d\u00a0Dogariu said. The concept may be developed to use in medical, chemical and other fields to move or separate small targeted items (such as bacteria or other biological entities) because of the different ways they would scatter the light.<\/p>\n
The team also included Dr. Sergey Sukhov, a senior research scientist in Â鶹ӳ»´«Ã½\u2019s College of Optics & Photonics, Veerachart Kajorndejnukul a Â鶹ӳ»´«Ã½ graduate student, and two scientists from National University of Singapore, Weiqiang Ding and Cheng-Wei Qiu.\u00a0<\/p>\n
The research was partially supported by the National Science Foundation and the Air Force Office of Scientific Research.<\/p>\n","protected":false},"excerpt":{"rendered":"When light falls on an object, it normally is pushed away. This is why, for instance, the dusty tails of comets are bent outward from the sun. But demonstrating the idea of using light to attract an object has long been an unattainable goal of scientists \u2013 until now. A team of researchers from the Â鶹ӳ»´«Ã½ and…","protected":false},"author":11,"featured_media":51791,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"template-twocol.php","format":"standard","meta":{"_acf_changed":false,"lazy_load_responsive_images_disabled":false,"footnotes":"","_links_to":"","_links_to_target":"","_wp_rev_ctl_limit":""},"categories":[23,24],"tags":[6395,5390,6396,10470],"tu_author":[],"class_list":["post-51783","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research","category-science-technology","tag-aristide-dogariu","tag-optics-and-photonics","tag-sergey-sukhov","tag-veerachart-kajorndejnukul"],"yoast_head":"\n