Design Considerations of Photonic THz Communications for 6G Networks

Large bandwidths at terahertz (THz) frequencies higher than 100 GHz have been garnering significant attention as key enablers for future wireless networks to provide data rates in the range of terabits per second, which is approximately one hundred times higher than the transmission rate of millimeter wireless systems. To fully utilize the merits of THz frequencies, devices with large operating bandwidths are highly desired. From this perspective, promising choices are photonic devices developed for fiber-optic communications, which have been commonly used since the early stages of THz communications research with different architectures and parameters. However, the factors limiting the performance of photonics-based THz systems have not yet been investigated thoroughly in terms of general system aspects. Here, we comprehensively analyze and compare various potential THz communications systems with a photonics-based THz transmitter. Based on modulation and optical light sources, we characterize the three most typical architectures and theoretically and experimentally analyze the impact of optical and phase noise on system performance.