In case if you have some general questions about the realization of visible light communications in OptiSystem software, please, take a look at the following link: https://optiwave.com/forums/topic/performance-analysis-of-visible-light-communication-system/. The other link considers OFDM implementation as well: https://optiwave.com/forums/topic/visible-light-coomunication/. I hope that it gives you some ideas. Otherwise, please give some more details about your question…