Physical Layer Secret Key Security of Liquid Crystal RIS-Aided Visible Light Communication Systems

This paper investigates the achievable secret key rate enhancement though the use of liquid crystal(LC) reconfigurable intelligent surfaces(RIS) aided receiver in visible visible light communication(VLC) systems. By adjusting the refractive index of the liquid crystal, the legitimate receiver' s channel can be improved. Thus, we formulate the achievable secret key rate maximization problem with respect to the refractive index of the LC RIS. To tackle this optimization problem, we employ the Sine-Cosine Algorithm (SCA). Simulation results demonstrate that the imployment of LC RIS-aided receiver and the proposed algorithm can significantly improve the system's achievable secret key rate compared to traditional benchmark methods. The SCA exhibits maintaining stable performance.