Photonic microwave oscillator using mode-locked laser as the high Q resonator

We show that an actively mode-locked laser can serve as a high Q microwave resonator in a photonic oscillator. The high Q is due to the high regenerative gain of the optical modes which generate a beat note at a photodetector as the microwave signal. In a fiber mode-locked laser setup, we have demonstrated the generation of a 10 GHz microwave signal with phase noise of -140 dBc/Hz at the offset frequency of 10 kHz. We have also found that the effective Q of the resonator depends on the optical pulse width.