Experimental Investigation of All-Optical Sub-THz Wavelength Conversion for 6G Communication Systems

Sub-terahertz (sub-THz) waves, operating in the 0.1-1 THz band, offer significant potential for next-generation 6G systems. These systems stand to benefit from photonic technologies that enable terabits-per-second communication with low latency and high throughput. This paper introduced, for the first time, a semiconductor optical amplifier (SOA) as a fast and reliable photonic-based technique for sub-THz wavelength conversion in fiber-based networks. The wavelength conversion leveraged nonlinear phenomena in the SOA, including cross-gain modulation, self-phase modulation, and four-wave mixing effects. Numerical simulations demonstrated an all-optical wavelength conversion capable of handling 100-GHz sub-THz signals with 16-ary quadrature amplitude modulation formats, achieving a data rate switching of 5 Gbps. Key system parameters were optimized, resulting in a 28.7 dB suppression ratio for the generated optical single sideband (OSSB) signal. Additionally, a proof-of-concept laboratory experiment validated the THz signal-switching concept. The proposed system incorporated a hybrid fiber/wireless channel and utilized various measures for performance evaluation.