Self-calibrating and high-sensitivity microwave phase noise analyzer applying an optical frequency comb generator and an optical-hybrid-based I/Q detector.

Phase noise analyzers (PNAs) are indispensable for evaluating the short-term stability of microwave signals. In this Letter, a high-sensitivity PNA with self-calibration capability is proposed based on an optical frequency comb generator and an optical-hybrid-based I/Q detector. The negative factors that result in inaccurate measurement, including the direct component interference, amplitude noises of the microwave signal under test and the laser, and phase noise of the laser, are all eliminated through digital signal processing. A proof-of-concept experiment is performed. The established PNA can achieve accurate phase noise measurement with a high sensitivity of -146.1  dBc/Hz at 10 kHz, and the self-calibrating property of the PNA is also verified.