Photonic-assisted wideband phase noise measurement of microwave signal sources

A photonic-assisted scheme for the phase noise measurement of microwave signal sources is proposed based on the optical delay-line method. In the proposed scheme, all the microwave signal processing is implemented in the optical domain, and the electrical devices that would limit the operation bandwidth and measurement sensitivity are avoided, leading to a large operation bandwidth and a high sensitivity. The feasibility of the proved phase noise measurement system is experimentally verified. A large operation bandwidth of 5-40 GHz is achieved, and a phase noise floor as low as -140 dBc/Hz at 10 kHz offset is obtained.