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Affolderbach, Christoph

Nom
Affolderbach, Christoph
Affiliation principale
Fonction
Collaborateur scientifique
Email
christoph.affolderbach@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/478
_
0000-0003-0733-2991

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  • Publication
    Accès libre
    Imaging microwave and DC magnetic fields in a vapor-cell Rb atomic clock
    (2015-11-6)
    Affolderbach, Christoph 
    ;
    Du, Guan-Xiang
    ;
    Bandi Nagabhushan, Thejesh 
    ;
    Horsley, Andrew
    ;
    Treutlein, Philipp
    ;
    Mileti, Gaetano 
    We report on the experimental measurement of the dc and microwave magnetic field distributions inside a recently developed compact magnetron-type microwave cavity mounted inside the physics package of a high-performance vapor-cell atomic frequency standard. Images of the microwave field distribution with sub-100-μm lateral spatial resolution are obtained by pulsed optical-microwave Rabi measurements, using the Rb atoms inside the cell as field probes and detecting with a CCD camera. Asymmetries observed in the microwave field images can be attributed to the precise practical realization of the cavity and the Rb vapor cell. Similar spatially resolved images of the dc magnetic field distribution are obtained by Ramsey-type measurements. The T2 relaxation time in the Rb vapor cell is found to be position dependent and correlates with the gradient of the dc magnetic field. The presented method is highly useful for experimental in situ characterization of dc magnetic fields and resonant microwave structures, for atomic clocks or other atom-based sensors and instrumentation.
  • Publication
    Accès libre
    Imaging Microwave and DC Magnetic Fields in a Vapor-Cell Rb Atomic Clock
    Affolderbach, Christoph 
    ;
    Du, Guan-Xiang
    ;
    Bandi, Thejesh
    ;
    Horsley, Andrew
    ;
    Treutlein, Philipp
    ;
    Mileti, Gaetano 
    We report on the experimental measurement of the dc and microwave magnetic field distributions inside a recently developed compact magnetron-type microwave cavity mounted inside the physics package of a high-performance vapor-cell atomic frequency standard. Images of the microwave field distribution with sub-100- μm lateral spatial resolution are obtained by pulsed optical-microwave Rabi measurements, using the Rb atoms inside the cell as field probes and detecting with a CCD camera. Asymmetries observed in the microwave field images can be attributed to the precise practical realization of the cavity and the Rb vapor cell. Similar spatially resolved images of the dc magnetic field distribution are obtained by Ramsey-type measurements. The T2 relaxation time in the Rb vapor cell is found to be position dependent and correlates with the gradient of the dc magnetic field. The presented method is highly useful for experimental in situ characterization of dc magnetic fields and resonant microwave structures, for atomic clocks or other atom-based sensors and instrumentation.
  • Publication
    Accès libre
    Characterization of Frequency-Doubled 1.5-μm Lasers for High-Performance Rb Clocks
    Almat, Nil 
    ;
    Moreno, William 
    ;
    Pellaton, Matthieu 
    ;
    Gruet, Florian 
    ;
    Affolderbach, Christoph 
    ;
    Mileti, Gaetano 
    We report on the characterization of two fiber-coupled 1.5- μm diode lasers, frequency-doubled and stabilized to Rubidium (Rb) atomic resonances at 780 nm. Such laser systems are of interest in view of their implementation in Rb vaporcell atomic clocks, as an alternative to lasers emitting directly at 780 nm. The spectral properties and the instabilities of the frequency-doubled lasers are evaluated against a state-of-the-art compact Rb-stabilized laser system based on a distributed-feedback laser diode emitting at 780 nm. All three lasers are frequency stabilized using essentially identical Doppler-free spectroscopy schemes. The long-term optical power fluctuations at 780 nm are measured, simultaneously with the frequency instability measurements done by three beat notes established between the three lasers. One of the frequency-doubled laser systems shows at 780 nm excellent spectral properties. Its relative intensity noise <10−12 Hz−1 is one order of magnitude lower than the reference 780-nm laser, and the frequency noise <106 Hz2/Hz is limited by the laser current source. Its optical frequency instability is <4 × 10−12 at τ = 1 s, limited by the reference laser, and better than 1 × 10−11 at all timescales up to one day. We also evaluate the impact of the laser spectral properties and instabilities on the Rb atomic clock performance, in particular taking into account the light-shift effect. Optical power instabilities on long-term timescales, largely originating from the frequency-doubling stage, are identified as a limitation in view of high-performance Rb atomic clocks.