Multichannel joint-polarization-frequency-modulation encrypted metasurface in secure THz communication

Since the discovery of wireless telegraphy, wireless communication via electromagnetic (EM) signals has become a standard solution to meet the growing demand for information transfer in modern society. To prevent counterfeiting and manipulation by unauthorized individuals, it is crucial to innovate and enhance security through information encryption. In this paper, we introduce a metasurface that controls the amplitude modulation at two different frequencies. Here, focusing on amplitude-frequency modulation for both x- and y-polarizations, we present an encrypted wireless communication protocol that uses the chaos algorithm to secure the target data and prevent eavesdroppers from accessing it. The encrypted data is transmitted through varying amplitudes at two different frequencies for both linear polarizations, achieved using two distinct graphene layers individually controlled by external biasing conditions. The extensive freedom enabled by simultaneous modulation of amplitude, frequency, and polarization allows information to be transmitted across many channels, thereby enhancing the security of encrypted information. The simulations demonstrate that encoding data, such as images, and transmitting it through amplitude-frequency modulation for both horizontal and vertical polarizations offers promising opportunities for various applications, including terahertz (THz) communications, anti-counterfeiting, THz data storage, and THz data transmission.