# Experimental Demonstration of Terahertz-Wave Signal Generation for 6G Communication Systems
## 4 Conclusions  
This paper presents a comprehensive study on the generation of a 0.1 THz photonic vector THz-wave signal utilizing a simple PM-based optical frequency comb and an IQ modulator for signal modulation, supported by experimental and simulation results from a photonic-based approach for THz signal generation in next-generation communication network applications. Through numerical simulations, we have demonstrated the feasibility of THz signal generation. The experimental setup, serving as a proof-of-concept, has  
Figure 15: EVM versus optical received power for QPSK THz signal over hybrid transmission (30 km SMF and 1 m RF wireless channel).  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Component** & **Model Number** \\ \hline Continuous wave (CW) & Koheras ADJUSTIK \\ Vector signal generator (VSG) & KEVSIGHT E8267D \\ Kamelian SOA & SOA-NL-L1-C-FA \\ Amonics SOA & SOA15-20-R \\ Amonics EDFA & EDFA-PA-40-B-FA \\ WSS & FINISAR WaveShaper 4000s 4903306 \\ IQ modulator & FUJITSU 78110 \\ Photodiode (PD) & FINISAR XPDV4121R 10 125 011 235130 B9W.0375 \\ Analyzer & Infiniuam DSO-X-93204A \\ Low-noise amplifier & QuinStar QLW-24403336-J0 \\ Horn antennas & SAGE SAR-2507-28-S2 \\ Digital storage oscilloscope & Keysight DSOX 932048 \\ Vector signal analyzer software & Keysight VSA 89600 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Components versus model.  
successfully generated and transmitted 4 Gbps QPSK signals at a frequency of 0.1 THz over a hybrid fiber/RF channel. The transmitted signal was received with BER and EVM below the FEC limit.  
In our experimental setup, we successfully generated and transmitted a 4 Gbps QPSK photonic vector THz wave signal. The process begins with a phase modulator driven by a 12.5 GHz radio frequency signal to generate an optical frequency comb. This comb undergoes heterodyne mixing in UTC-PD, producing a 0.1 THz radio frequency signal. The THz signal is then transmitted over a 30 km span of single-mode fiber, operating in a hybrid mode. The resulting electrical 0.1 THz vector signal, modulated with QPSK, achieves a (BER below the threshold of \(3.8\times 10^{-3}\) corresponding to the HD-FEC limit.  
This study provides valuable insights for further research into high-frequency vector THz-wave signal generation, highlighting that advancements in related optical devices will significantly enhance the development of photonic THz-wave signal generation technology, promising a bright future for this field.  
Conceptualization, Y.A. and A.M.R.; Methodology, Y.A.; Software, A.M.R.; Validation, A.M.R., F.M.I. and S.A.A.; Formal analysis, Y.A.; Investigation, Y.A. and M.A.E.; Resources, A.M.R.; Writing--original draft, Y.A.; Writing--review & editing, Y.A., M.A.E. and S.A.A.; Supervision, A.M.R., S.M.I., F.M.I. and S.A.A.; Project administration, S.A.A.; Funding acquisition, M.A.E. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Researchers Supporting Project, King Saud University, Riyadh, Saudi Arabia, under Grant RSP2025R46.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.