Researchers have developed a compact photonic terahertz synthesizer that combines low-noise frequency generation, high-speed wireless communication, and parallel coherent terahertz carrier generation in a single Kerr microcomb platform. The approach could provide a practical route toward compact and scalable terahertz systems for future communication, sensing, and precision measurement.
Terahertz frequencies offer large spectral bandwidths that are attractive for high-capacity wireless communication and high-resolution sensing. However, generating stable and low-noise terahertz signals remains challenging. Electronic frequency multiplication can accumulate phase noise at high frequencies, while many photonic approaches rely on ultrastable optical references and complex feedback systems.
To address these limitations, researchers from Nanjing University, Southeast University, Purple Mountain Laboratories, and the Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, developed a packaged Kerr microcomb based on a self-injection-locked fiber Fabry–Pérot resonator (FFPR).
In the system, optical feedback from the FFPR stabilizes a distributed-feedback laser and significantly reduces its frequency noise. The researchers measured an instantaneous Lorentzian pump linewidth as narrow as 0.386 Hz and generated stable Kerr soliton states with a fundamental repetition rate of 20.293 GHz. This compact self-injection-locking architecture reduces the need for bulky ultrastable references and complex external feedback.
The team then used optical comb lines to synthesize signals in the terahertz range and demonstrated a 319 GHz carrier for free-space wireless communication. The signal was transmitted over a 5-meter link using both 16-QAM and 64-QAM modulation at symbol rates of up to 15 GBd. The measured bit-error rates remained below the soft-decision forward-error-correction threshold.
To evaluate practical stability, the researchers repeatedly switched the system off and on and recovered the target operating state. Similar communication performance was obtained after each restart, demonstrating reproducible turnkey operation.
Beyond single-carrier transmission, the same microcomb was used to generate multiple mutually coherent terahertz frequency comb with a spacing of 20.293 GHz. Five signals were experimentally characterized, all showing narrow spectral features and preserved coherence. This multi-carrier capability allows data to be distributed across several frequency channels instead of relying on a single extremely broadband channel.
By combining compact packaging, low-noise terahertz synthesis, high-order wireless modulation, and parallel coherent carrier generation, the platform offers a scalable photonic approach for future terahertz systems. Further improvements in resonator performance and system integration could extend the technology toward high-capacity multi-channel wireless communication, sensing, coherent radar, and precision spectroscopy.
Experimental study
Not applicable
Compact low-noise photonic-terahertz synthesizer
21-Sep-2026
The authors declare that they have no conflict of interest.