We report on preliminarily results of push-pull optical pumping (PPOP) on the D1-transition of cesium. PPOP is based on a coherent population trapping effect prepared with polarization-modulated bichromatic light coupling the two ground-state hyperfine levels, the light polarization being modulated at the microwave frequency. With a suitable choice of polarizations, a single specific coherent superposition (dark state) formed by the two mF= 0 sublevels can be prepared under optimal conditions. This increase the contrast of the clock reference signal without significant line-broadening.We report on preliminarily results of push-pull optical pumping (PPOP) on the D1-transition of cesium. PPOP is based on a coherent population trapping effect prepared with polarization-modulated bichromatic light coupling the two ground-state hyperfine levels, the light polarization being modulated at the microwave frequency. With a suitable choice of polarizations, a single specific coherent superposition (dark state) formed by the two mF= 0 sublevels can be prepared under optimal conditions. This increase the contrast of the clock reference signal without significant line-broadening.

European Frequency and Time ForumApr 1, 20120 citations

Coherent-population-trapping resonances in buffer-gas-filled Cs-vapor cells with push-pull optical pumping

Xiaochi Liu, Jean-Marc Mérolla, Stéphane Guérandel +3 more

We report on a theoretical study and experimental characterization of coherent-population-trapping (CPT) resonances in buffer-gas-filled vapor cells with push-pull optical pumping (PPOP) on Cs ${D}_{1}$ line. We point out that the push-pull interaction scheme is identical to the so-called $\mathrm{lin}\ensuremath{\perp}\mathrm{lin}$ polarization scheme. Expressions of the relevant dark states, as well as of absorption, are reported. The experimental setup is based on the combination of a distributed feedback diode laser, a pigtailed intensity Mach-Zehnder electro-optic modulator (MZ EOM) for optical sideband generation and a Michelson-like interferometer. A microwave technique to stabilize the transfer function operating point of the MZ EOM is implemented for proper operation. A CPT resonance contrast as high as 78 $%$ is reported in a cm-scale cell for the magnetic-field-insensitive clock transition. The impact of the laser intensity on the CPT-clock signal key parameters (linewidth, contrast, linewidth/contrast ratio) is reported for three different cells with various dimensions and buffer-gas contents. The potential of the PPOP technique for the development of high-performance atomic vapor-cell clocks is discussed.We report on a theoretical study and experimental characterization of coherent-population-trapping (CPT) resonances in buffer-gas-filled vapor cells with push-pull optical pumping (PPOP) on Cs ${D}_{1}$ line. We point out that the push-pull interaction scheme is identical to the so-called $\mathrm{lin}\ensuremath{\perp}\mathrm{lin}$ polarization scheme. Expressions of the relevant dark states, as well as of absorption, are reported. The experimental setup is based on the combination of a distributed feedback diode laser, a pigtailed intensity Mach-Zehnder electro-optic modulator (MZ EOM) for optical sideband generation and a Michelson-like interferometer. A microwave technique to stabilize the transfer function operating point of the MZ EOM is implemented for proper operation. A CPT resonance contrast as high as 78$%$ is reported in a cm-scale cell for the magnetic-field-insensitive clock transition. The impact of the laser intensity on the CPT-clock signal key parameters (linewidth, contrast, linewidth/contrast ratio) is reported for three different cells with various dimensions and buffer-gas contents. The potential of the PPOP technique for the development of high-performance atomic vapor-cell clocks is discussed.

arXiv:1302.3724Physical Review AJan 17, 201377 citations

Ramsey spectroscopy of high-contrast CPT resonances with push-pull optical pumping in Cs vapor

Xiaochi Liu, Jean-Marc Mérolla, Stéphane Guérandel +2 more

We report on the detection of high-contrast and narrow Coherent Population Trapping (CPT) Ramsey fringes in a Cs vapor cell using a simple-architecture laser system. The latter allows the combination of push-pull optical pumping (PPOP) and a temporal Ramsey-like pulsed interrogation. An originality of the optics package is the use of a single Mach-Zehnder electro-optic modulator (MZ EOM) both for optical sidebands generation and light switch for pulsed interaction. Typical Ramsey fringes with a linewidth of 166 Hz and a contrast of 33 % are detected in a cm-scale buffer-gas filled Cs vapor cell. This technique could be interesting for the development of high-performance and low power consumption compact vapor cell clocks based on CPT.We report on the detection of high-contrast and narrow Coherent Population Trapping (CPT) Ramsey fringes in a Cs vapor cell using a simple-architecture laser system. The latter allows the combination of push-pull optical pumping (PPOP) and a temporal Ramsey-like pulsed interrogation. An originality of the optics package is the use of a single Mach-Zehnder electro-optic modulator (MZ EOM) both for optical sidebands generation and light switch for pulsed interaction. Typical Ramsey fringes with a linewidth of 166 Hz and a contrast of 33 % are detected in a cm-scale buffer-gas filled Cs vapor cell. This technique could be interesting for the development of high-performance and low power consumption compact vapor cell clocks based on CPT.

arXiv:1305.7321Optics ExpressMay 14, 201350 citations

We report on a theoretical study and experimental characterization of coherent-population-trapping (CPT) resonances in buffer-gas-filled vapor cells with push-pull optical pumping (PPOP) on Cs

{D}_{1}

line. We point out that the push-pull interaction scheme is identical to the so-called $\mathrm{lin}\ensuremath{\perp}\mathrm{lin}$ polarization scheme. Expressions of the relevant dark states, as well as of absorption, are reported. The experimental setup is based on the combination of a distributed feedback diode laser, a pigtailed intensity Mach-Zehnder electro-optic modulator (MZ EOM) for optical sideband generation and a Michelson-like interferometer. A microwave technique to stabilize the transfer function operating point of the MZ EOM is implemented for proper operation. A CPT resonance contrast as high as 78

%

is reported in a cm-scale cell for the magnetic-field-insensitive clock transition. The impact of the laser intensity on the CPT-clock signal key parameters (linewidth, contrast, linewidth/contrast ratio) is reported for three different cells with various dimensions and buffer-gas contents. The potential of the PPOP technique for the development of high-performance atomic vapor-cell clocks is discussed.