This paper explains a phase-stabilization method for photomixing-based terahertz (THz) wave generation. The system uses a backward-propagating pilot lightwave to detect and correct phase drift in real time. A proportional-integral-derivative (PID) controller and a phase shifter (PS) are used to keep the optical phase difference Δϕ steady. In the optical-domain test, the system reduced phase noise by about 13 dB on average, with the highest improvement of nearly 16 dB at a 5 kHz offset frequency. These results show that the feedback control can stabilize the optical phase and maintain steady performance. This work gives confidence that the same system can be used to generate stable and coherent THz waves in future photomixing experiments.
IBRAHIM et al. (Thu,) studied this question.