Using subwavelength and nanometer / micrometer diameter optical fibers to capture and manipulate microparticle with light is one of the hot spots in international research at present. This technique can deal with microparticle from several nanometers to tens of nanometers, large biological molecule and cell without contact or harm. It has a great potential for application in the area of physics, chemistry, biology and medicine. One of the vital difficulties is how to eliminate microparticle and bacteria with drinking water, especially with the medical water.

To solve the problem, Xin Hongbao, an undergraduate from School of Physics and Engineering, under the instruction of Professor Li Baojun, cleverly made a 6-micrometer-diameter optical fiber to an optical fiber ring. The optical fiber ring was put into water full of 2-micrometer microparticle and supplied with near infrared (wavelength 1.55 micrometer, luminous power 97mw) The experiment have successfully gathered and manipulated the microparticle. Xin Hongbao observed and analyzed the phenomenon.

The result was published in an important academic journal Optics Express in February 2011. (The paper can be found in http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-19-3-2711) Two reviewers of Optics Express gave their comments, “The authors’ reported work is excellent.” “This manuscript describes a demonstration of optical purification of water with an optical fiber-ring by combining photophoresis and temperature gradient. The results are interesting and the technique can be applied in local water purification.”Moreover, the result was introduced by TPDSci (www.tpdsci.com, an online publication providing a comprehensive review of interdisciplinary topics in the particle and particle dispersion science) .

Xin Hongbao, from Jiangxi Province, got admitted to the School of Physics and Engineering in 2007. He was in the Sun Yat-Sen class, a class specially set for outstanding students in SYSU. Now he is a senior. Ever since 2007, he had won the first prize scholarship in Sun Yat-Sen University and the scholarship of national encouragement.