title: Phase Analysis for Frequency Standards in the Microwave and Optical Domains.
abstract: Coherent manipulation of atomic states is a key concept in high-precision spectroscopy and used in atomic fountain clocks and a number of optical frequency standards. Operation of these standards can involve a number of cyclic switching processes, which may induce cycle-synchronous phase excursions of the interrogation signal and thus lead to shifts in the output of the frequency standard. We have built a field-programmable gate array (FPGA)-based phase analyzer to investigate these effects and conducted measurements on two kinds of frequency standards. For the caesium fountains PTB-CSF1 and PTB-CSF2, we were able to exclude phase variations of the microwave source at the level of a few microradians, corresponding to relative frequency shifts of less than [Formula: see text]. In the optical domain, we investigated phase variations in PTB's Yb (+) optical frequency standard and made detailed measurements of acousto-optic modulator (AOM) chirps and their scaling with duty cycle and driving power. We ascertained that cycle-synchronous as well as long-term phase excursion do not cause frequency shifts larger than [Formula: see text].
authors.forename: Michael
authors.initials: M
authors.lastname: Kazda
authors.forename: Vladislav
authors.initials: V
authors.lastname: Gerginov
authors.forename: Nils
authors.initials: N
authors.lastname: Huntemann
authors.forename: Burghard
authors.initials: B
authors.lastname: Lipphardt
authors.forename: Stefan
authors.initials: S
authors.lastname: Weyers