arXiv:0707.2930 · Optics Letters

Strong saturation absorption imaging of dense clouds of ultracold atoms

Gael Reinaudi, Thierry Lahaye, Z. Wang, David Guéry-Odelin

Published Oct 23, 2007• 231 citations

Abstract

We report on a far above saturation absorption imaging technique to investigate the characteristics of dense packets of ultracold atoms. The transparency of the cloud is controlled by the incident light intensity as a result of the nonlinear response of the atoms to the probe beam. We detail our experimental procedure to calibrate the imaging system for reliable quantitative measurements and demonstrate the use of this technique to extract the profile and its spatial extent of an optically thick atomic cloud.

DOI: 10.1364/ol.32.003143

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arXiv:0707.2930 · Optics Letters

Strong saturation absorption imaging of dense clouds of ultracold atoms

Gael Reinaudi, Thierry Lahaye, Z. Wang, David Guéry-Odelin

Published Oct 23, 2007• 231 citations

arXiv HTML PDF

Abstract

DOI: 10.1364/ol.32.003143

Related papers

Calibration of saturation absorption imaging of ultracold atom clouds

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We describe an experimental method to calibrate an absorption imaging system for ultracold atom clouds. Optical density profiles of an atom cloud are obtained for various probe beam intensities and are analyzed to determine the correction factor for the effective probe beam intensity directly from saturation effects. We find that the temporal shape of the probe-beam pulse needs to be taken into account for a quantitative analysis of the optical density measured in saturation absorption imaging. We show that this pulse-shape effect can lead to distortion of the density profile due to its nonlinear dependence on the optical depth.We describe an experimental method to calibrate an absorption imaging system for ultracold atom clouds. Optical density profiles of an atom cloud are obtained for various probe beam intensities and are analyzed to determine the correction factor for the effective probe beam intensity directly from saturation effects. We find that the temporal shape of the probe-beam pulse needs to be taken into account for a quantitative analysis of the optical density measured in saturation absorption imaging. We show that this pulse-shape effect can lead to distortion of the density profile due to its nonlinear dependence on the optical depth.

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We demonstrate that phase-contrast imaging (PCI) can reliably reconstruct the in situ density profile even for highly spatially and optically dense samples. In our experiment, we achieve high spatial densities of up to 7.9 × 1013 atoms/cm3 and optical depths up to 64 in a dense cold atomic cloud of 88Sr atoms. The use of a spatial light modulator instead of a fixed phase plate in the PCI setup provides enhanced flexibility and control of imaging parameters, making this imaging technique robust against imaging artifacts and adaptable to varying experimental conditions. Moreover, we quantify the conditions under which the standard single-atom polarizability model remains accurate for PCI in a density regime where collective effects should modify the atomic response of the system. We experimentally validate our statements by showing excellent agreement with time-of-flight measurements even at the highest densities. Our results establish PCI as a reliable and versatile method for characterizing spatially dense atomic clouds.We demonstrate that phase-contrast imaging (PCI) can reliably reconstruct the in situ density profile even for highly spatially and optically dense samples. In our experiment, we achieve high spatial densities of up to 7.9 × 1013 atoms/cm3 and optical depths up to 64 in a dense cold atomic cloud of 88Sr atoms. The use of a spatial light modulator instead of a fixed phase plate in the PCI setup provides enhanced flexibility and control of imaging parameters, making this imaging technique robust against imaging artifacts and adaptable to varying experimental conditions. Moreover, we quantify the conditions under which the standard single-atom polarizability model remains accurate for PCI in a density regime where collective effects should modify the atomic response of the system. We experimentally validate our statements by showing excellent agreement with time-of-flight measurements even at the highest densities. Our results establish PCI as a reliable and versatile method for characterizing spatially dense atomic clouds.

Review of Scientific InstrumentsAug 1, 20251 citation

We present the experimental production and characterization of a dense cold atomic cloud of

^{88}\text{Sr}

atoms, optimized for the future studies of light transport in highly dense regimes. Using narrow-line molasses on the 689 nm transition, combined with a far off-resonant optical dipole trap, we achieve spatial densities as high as

7.9 \times 10^{13} \, \text{atoms/cm}^3

and optical depths up to 64. This approach stands out from previous methods by integrating narrow-line molasses with an optical dipole trap, enabling high-density samples without relying on evaporative cooling. Unlike traditional absorption imaging, which becomes inaccurate in such dense regimes, we demonstrate that phase-contrast imaging (PCI) can reliably reconstruct the in-situ density profile even for highly spatially and optically dense samples. The use of a spatial light modulator instead of a fixed phase plate in the PCI setup provides enhanced flexibility and control of imaging parameters, making this imaging technique robust against imaging artifacts and adaptable to varying experimental conditions. Moreover, we derive theoretical conditions for reliable PCI operation in dense regimes and validate these experimentally, showing excellent agreement with time-of-flight measurements even at the highest densities. Our results establish a robust method for producing and characterizing dense atomic clouds.