Gereration of microwaves with ultra-low phase-noise from an optical clock

Frequency stabilized lasers have significant advantages for generating microwave signals with unprecedented stability and ultralow phase-noise. We report the optical generation of 10 GHz microwave signals with phase-noise close to the carrier that is > 40 dB better than achieved with state-of-the-art microwave sources and high quality microwave synthesizers. The method uses stable lasers locked to optical resonators that have extremely high Q´s and the frequency can be steered in the longer term to atomic resonances. An optical frequency divider is implemented with a femtosecond laser based optical frequency comb, which coherently divides the optical frequency to the microwave range