With the prosperous development of LED industry and changing communication technologies, “visible light communication” technology which skillfully combines LED lighting with optical communication is coming into people’s sight, Taking visible light as a signal carrier, this technology can realize high-speed data transmission through the high-frequency flickering of light source. Thanks to the characteristics of LED light source, the visible light communication features high transmission speed, good system security, low power consumption and electromagnetic radiation when compared with traditional wireless communication band. 

As a new communication technology, the visible light communication has a wide application market prospect. Indoor networking, positioning service and traffic service can be combined with visible light communication, bringing unparalleled innovation application and value experience to IoT, smart city and intelligent transportation system. Because of this, it has attracted the worldwide attention. According to the latest research report of Grand View Research, the global market of visible light communication is expected to be USD 101.3 billion in 2024. 

As a traditional white light LED (blue light LED exciting yellow fluorescent powder) of the important signal source of visible light communication, the fluorescent lifetime of fluorescent powder is long, and the modulation bandwidth is narrow, which is one of the bottlenecks for further improvement of visible light communication transmission rate. As a new nanocrystalline material, the fluorescent lifetime of quantum dot is far shorter than the traditional fluorescent powder, which can significantly improve the smearing of traditional white light LED, enhance the modulation bandwidth of white light LED and help enhance the visible light communication rate. 

Based on this idea, Xiao Xiangtian, Tang Haodong and Zhang Tianqi, undergraduates of SUSTC-EEE, have carried out research under the guidance of Assistant Professor Wang Kai and Associate Professor Wang Rui. Relevant research paper Improving the Modulation Bandwidth of LED by CdSe/ZnS Quantum Dots for Visible Light Communication (the first authors Xiao Xiangtian and Tang Haodong) was published in Optics Express (Optics Express, Impact Factor 3.148, JCR Q1), an international academic journal under Optical Society of America (OSA). This research proposes a new method in which visible light communication transmission rate can be improved by the white light LED of quantum dot of modulation bandwidth and develops new quantum dot composite material (QLMS) to widen the white light LED bandwidth based on such features that the fluorescent lifetime of quantum dot material is relatively short and the modulation bandwidth is relatively wide and improve 67.75% when compared with the white light LED of traditional fluorescent powder. Meanwhile, modeling analysis is conducted for internal link between modulation bandwidth and fluorescent lifetime. 

This research is funded by National Natural Science Foundation of China (51402148), Guangdong “Special Support Program” (2014TQ01C494), Shenzhen Overseas High-level Talents Innovation and Entrepreneurship Program (KQCX20140522151322950) and Special Fund Program for Technical Innovation and Cultivation of Guangdong University Students (“Climbing Plan”) (PDJH2016b0440). 

Article link: https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-19-21577, doi: 10.1364/OE.24.021577