Ultra-low phase noise frequency synthesis from optical atomic frequency standards

We discuss frequency synthesizer needs and recent phase noise results of a multi-level frequency divider that are consistent with the phase noise of new high-accuracy optical atomic standards. Optical atomic standards achieve extremely low frequency uncertainties in less than hundreds of seconds due to their unprecedented phase stability and accuracy. The desire for low white-FM noise that ordinarily required days of averaging for laboratory standards to attain full accuracy has been shifted to a need for low flicker-FM noise to maintain long-term frequency uncertainty with only seconds of averaging. This imposes new requirements for low levels of phase noise realizable by laser stabilization by a hi-Q optical cavity of a phase-coherent optical frequency comb. The multi-level frequency divider serves as a tool for synthesizing many low-phase noise frequencies.