Secure visible light communication system with liquid crystal cell modulation

We propose and experimentally demonstrate a secure visible light communication (VLC) system using light-emitting diode and liquid crystal cell. By employing this secure VLC system, transmitted data with useful message can be well protected and received by authorized users. After applying the pre-emphasis and zero-padding technique, clear eye diagrams and high bit error rate performance for the deciphered signal were obtained. We also report the optimal amplitude range for original message data and encryption signals. In addition, the influence of the proposed security process on the broadcast VLC system was explored.