Modeling and Analysis for Modulation of Light-Conversion Materials in Visible Light Communication

Visible light communication (VLC) is a kind of high-efficiency wireless communication technology. As one of the key issues in VLC, the modulation bandwidth of light-conversion materials based light-emitting diodes (LEDs) has gained considerable attention in recent years. However, few people focus on theoretical analyses of the light-conversion process during modulation, which show significant influence on the modulation bandwidth of a white LED. In this work, we proposed low-pass filter based models of light-conversion materials of YAG:Ce phosphor and CdSe/ZnS quantum dots, to build the relationship between fluorescence lifetime of these light-conversion materials and their modulation bandwidth. Furthermore, the modulation bandwidth of light source with polychromatic light was obtained and analyzed based on the proposed model. The experimental results of the modulation bandwidth showed a highly consistency with the results from simulation models. These analyses were believed to help realizing white-light illumination with high bandwidth. To the best of our knowledge, this is the first time the modulation mechanisms of light-conversion materials in VLC have been comprehensively discussed in literature.