laser light is tuned to pump atoms predominantly from the lower ground-state hyperfine multiplet. One can understand the signal reversals in a simple, semiquantitative way with reference to the spin-temperature distribution. Quantitative computer simulations are in excellent agreement with observations.

Related papers

Magnetic resonance reversals in optically pumped alkali-metal vapor

F. Gong, Yuan‐Yu Jau, W. Happer

We report an unusual phenomenon, peculiar sign reversals of the ground-state magnetic resonances and of the zero-dip resonance (Zeeman resonance at zero field) of optically pumped, alkali-metal vapors. These anomalies occur when a weak circularly polarized $D1$ laser light is tuned to pump atoms predominantly from the lower ground-state hyperfine multiplet. One can understand the signal reversals in a simple, semiquantitative way with reference to the spin-temperature distribution. Quantitative computer simulations are in excellent agreement with observations.We report an unusual phenomenon, peculiar sign reversals of the ground-state magnetic resonances and of the zero-dip resonance (Zeeman resonance at zero field) of optically pumped, alkali-metal vapors. These anomalies occur when a weak circularly polarized $D1$ laser light is tuned to pump atoms predominantly from the lower ground-state hyperfine multiplet. One can understand the signal reversals in a simple, semiquantitative way with reference to the spin-temperature distribution. Quantitative computer simulations are in excellent agreement with observations.

Physical Review AMay 25, 20075 citations

Cesium optical-radio-frequency resonance line reversals and doubling

Feiyun Fang, Xiaochao Cao, Yao Hu +2 more

We report an experimental study on the ground-state magnetic resonances of optically pumped cesium vapors at lower temperatures of about 30°C–40°C. A longitudinal static magnetic field is applied along the single laser beam to control the splitting of the Zeeman sublevels of the ground state. When the laser frequency is set to the cesium D1 spectral line (F=3→F′=4), by modifying the transverse radio frequency field, we find that the unusual weaker-absorption and zero-dip resonance phenomena occur in the optical-magnetic resonance (OMR) effects, which is called the cesium optical-RF resonance line reversals and doubling in this paper. We explore a theoretical description for these phenomena by using density matrix equations, and our calculated results are in approximate agreement with the experimental results.We report an experimental study on the ground-state magnetic resonances of optically pumped cesium vapors at lower temperatures of about 30°C–40°C. A longitudinal static magnetic field is applied along the single laser beam to control the splitting of the Zeeman sublevels of the ground state. When the laser frequency is set to the cesium D1 spectral line (F=3→F′=4), by modifying the transverse radio frequency field, we find that the unusual weaker-absorption and zero-dip resonance phenomena occur in the optical-magnetic resonance (OMR) effects, which is called the cesium optical-RF resonance line reversals and doubling in this paper. We explore a theoretical description for these phenomena by using density matrix equations, and our calculated results are in approximate agreement with the experimental results.

Journal of the Optical Society of America BJan 31, 20190 citations

Linewidths of the 0-0 hyperfine transition in optically pumped alkali-metal vapors

James C. Camparo, R. P. Frueholz

A generalized model for the magnetic resonance signal corresponding to the 0-0 hyperfine transition in an optically pumped alkali-metal vapor is presented. Under conditions of microwave power broadening, the model predicts ``anomalous'' light broadening and ``anomalous'' relaxation narrowing of the magnetic resonance linewidth. Good agreement between theory and experiment was obtained in an experiment that confirmed the prediction of anomalous light broadening. These results show that the 0-0 hyperfine transition cannot be described as a simple two-level system; rather, the alkali-atom's nuclear spin plays an important role in determining the magnetic resonance linewidth.A generalized model for the magnetic resonance signal corresponding to the 0-0 hyperfine transition in an optically pumped alkali-metal vapor is presented. Under conditions of microwave power broadening, the model predicts ``anomalous'' light broadening and ``anomalous'' relaxation narrowing of the magnetic resonance linewidth. Good agreement between theory and experiment was obtained in an experiment that confirmed the prediction of anomalous light broadening. These results show that the 0-0 hyperfine transition cannot be described as a simple two-level system; rather, the alkali-atom's nuclear spin plays an important role in determining the magnetic resonance linewidth.

Physical Review AMar 1, 198541 citations

Anomalous Level-crossing Resonances in Rb Vapor Cells with Buffer Gas

Wei Xiao, Meng Liu, Teng Wu +2 more

SummaryThe ground-state level-crossing resonance, or Hanle resonance, in atomic vapors are widely used for atomic magnetometry. In this paper, we report observations of anomalous level-crossing resonances for Rb vapor in a buffer-gas cell. By optically pumping alkali atoms with a ring-shaped laser beam and detecting the spin polarization in the hole of the pumping light with an off-resonance light, we observe a polarization reversion when scanning the transverse magnetic field around zero. Both experiments and simulations are demonstrated.SummaryThe ground-state level-crossing resonance, or Hanle resonance, in atomic vapors are widely used for atomic magnetometry. In this paper, we report observations of anomalous level-crossing resonances for Rb vapor in a buffer-gas cell. By optically pumping alkali atoms with a ring-shaped laser beam and detecting the spin polarization in the hole of the pumping light with an off-resonance light, we observe a polarization reversion when scanning the transverse magnetic field around zero. Both experiments and simulations are demonstrated.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)Apr 24, 20220 citations

Light narrowing of magnetic resonance lines in dense, optically pumped alkali-metal vapor

Natarajan D. Bhaskar, James C. Camparo, W. Happer +1 more

A new and unusual phenomenon which we call light narrowing is reported and discussed in this paper. We discovered this effect in dense, spin-polarized cesium vapor optically pumped with a cw blue dye laser beam tuned to the second resonance ${D}_{1}$ line (4593 \AA{}). We observe a significant narrowing of the radio-frequency power-broadened magnetic resonance lines (linewidths narrow by as much as a factor of 2.5) when the intensity of the circularly polarized incident dye laser beam is increased by either focusing the beam or by the removal of attenuating filters from the focused beam. The magnetic resonance linewidths in spin-polarized cesium vapor were measured over a wide range of cesium number densities (5\ifmmode\times\else\texttimes\fi{} ${10}^{12}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ \ensuremath{\le}[Cs]\ensuremath{\le}1\ifmmode\times\else\texttimes\fi{} ${10}^{16}$ ${\mathrm{cm}}^{\ensuremath{-}3}$). This corresponds to cesium spinexchange rates of 4.5\ifmmode\times\else\texttimes\fi{} ${10}^{3}$ to 9\ifmmode\times\else\texttimes\fi{} ${10}^{6}$ ${\mathrm{sec}}^{\ensuremath{-}1}$. For low cesium number densities (5\ifmmode\times\else\texttimes\fi{} ${10}^{12}$ [Cs]3\ifmmode\times\else\texttimes\fi{} ${10}^{14}$ ${\mathrm{cm}}^{\ensuremath{-}3}$) the light-narrowing effect is large (a factor of 2.5) and independent of [Cs]. In the region of 3\ifmmode\times\else\texttimes\fi{} ${10}^{14}$ to 1\ifmmode\times\else\texttimes\fi{} ${10}^{15}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ in number densities, the light-narrowing effect decreases with increasing [Cs]. At high cesium number densities ([Cs]> 1\ifmmode\times\else\texttimes\fi{} ${10}^{15}$ ${\mathrm{cm}}^{\ensuremath{-}3}$) this light-narrowing effect almost completely disappears. In the limit of low-radio-frequency power the magnetic resonance linewidths for focused and unfocused dye laser beam are nearly the same. Experimental observations on this new effect are presented in detail. In the latter part of this paper a self-contained theoretical treatment of the light-narrowing effect is developed. Using Bloch equations in the presence of optical pumping, spin relaxation (diffusion, electron randomization), rapid spin exchange, and radio-frequency magnetic field, expressions for magnetic resonance line shapes are derived. In general, we find good agreement between our experimental results and the theory.A new and unusual phenomenon which we call light narrowing is reported and discussed in this paper. We discovered this effect in dense, spin-polarized cesium vapor optically pumped with a cw blue dye laser beam tuned to the second resonance ${D}_{1}$ line (4593 \AA{}). We observe a significant narrowing of the radio-frequency power-broadened magnetic resonance lines (linewidths narrow by as much as a factor of 2.5) when the intensity of the circularly polarized incident dye laser beam is increased by either focusing the beam or by the removal of attenuating filters from the focused beam. The magnetic resonance linewidths in spin-polarized cesium vapor were measured over a wide range of cesium number densities (5\ifmmode\times\else\texttimes\fi{}${10}^{12}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ \ensuremath{\le}[Cs]\ensuremath{\le}1\ifmmode\times\else\texttimes\fi{}${10}^{16}$ ${\mathrm{cm}}^{\ensuremath{-}3}$). This corresponds to cesium spinexchange rates of 4.5\ifmmode\times\else\texttimes\fi{}${10}^{3}$ to 9\ifmmode\times\else\texttimes\fi{}${10}^{6}$ ${\mathrm{sec}}^{\ensuremath{-}1}$. For low cesium number densities (5\ifmmode\times\else\texttimes\fi{}${10}^{12}$ [Cs]3\ifmmode\times\else\texttimes\fi{}${10}^{14}$ ${\mathrm{cm}}^{\ensuremath{-}3}$) the light-narrowing effect is large (a factor of 2.5) and independent of [Cs]. In the region of 3\ifmmode\times\else\texttimes\fi{}${10}^{14}$ to 1\ifmmode\times\else\texttimes\fi{}${10}^{15}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ in number densities, the light-narrowing effect decreases with increasing [Cs]. At high cesium number densities ([Cs]> 1\ifmmode\times\else\texttimes\fi{}${10}^{15}$ ${\mathrm{cm}}^{\ensuremath{-}3}$) this light-narrowing effect almost completely disappears. In the limit of low-radio-frequency power the magnetic resonance linewidths for focused and unfocused dye laser beam are nearly the same. Experimental observations on this new effect are presented in detail. In the latter part of this paper a self-contained theoretical treatment of the light-narrowing effect is developed. Using Bloch equations in the presence of optical pumping, spin relaxation (diffusion, electron randomization), rapid spin exchange, and radio-frequency magnetic field, expressions for magnetic resonance line shapes are derived. In general, we find good agreement between our experimental results and the theory.

Physical Review AJun 1, 198153 citations

Anomalous narrowing of magnetic-resonance linewidths in optically pumped alkali-metal vapors

T. McClelland, L. K. Lam, T. M. Kwon

Narrowing of magnetic-resonance lines in a dense optically pumped alkali-metal vapor ${(}^{87}$ Rb) has been observed. This observation is shown to be a result of optical pumping with a monochromatic light source tuned such that the real part of the vapor polarizability, which is responsible for light shifts, is essentially zero. A model based on the Bloch equations is used to describe the observed narrowing effect, and results of numerical calculations based on this model are presented. The results agree qualitatively with observations, and show correctly the disappearance of the effect at low light levels. This narrowing effect is of importance to the development of precision frequency standards and magnetometers utilizing monochromatic light sources (such as semiconductor lasers).Narrowing of magnetic-resonance lines in a dense optically pumped alkali-metal vapor ${(}^{87}$Rb) has been observed. This observation is shown to be a result of optical pumping with a monochromatic light source tuned such that the real part of the vapor polarizability, which is responsible for light shifts, is essentially zero. A model based on the Bloch equations is used to describe the observed narrowing effect, and results of numerical calculations based on this model are presented. The results agree qualitatively with observations, and show correctly the disappearance of the effect at low light levels. This narrowing effect is of importance to the development of precision frequency standards and magnetometers utilizing monochromatic light sources (such as semiconductor lasers).

Physical Review AMar 1, 19866 citations

D1

D1

{D}_{1}

line (4593 \AA{}). We observe a significant narrowing of the radio-frequency power-broadened magnetic resonance lines (linewidths narrow by as much as a factor of 2.5) when the intensity of the circularly polarized incident dye laser beam is increased by either focusing the beam or by the removal of attenuating filters from the focused beam. The magnetic resonance linewidths in spin-polarized cesium vapor were measured over a wide range of cesium number densities (5\ifmmode\times\else\texttimes\fi{}

{10}^{12}

${\mathrm{cm}}^{\ensuremath{-}3}$ \ensuremath{\le}[Cs]\ensuremath{\le}1\ifmmode\times\else\texttimes\fi{}

{10}^{16}

${\mathrm{cm}}^{\ensuremath{-}3}$). This corresponds to cesium spinexchange rates of 4.5\ifmmode\times\else\texttimes\fi{}

{10}^{3}

to 9\ifmmode\times\else\texttimes\fi{}

{10}^{6}

${\mathrm{sec}}^{\ensuremath{-}1}$. For low cesium number densities (5\ifmmode\times\else\texttimes\fi{}

{10}^{12}

[Cs]3\ifmmode\times\else\texttimes\fi{}

{10}^{14}

${\mathrm{cm}}^{\ensuremath{-}3}$) the light-narrowing effect is large (a factor of 2.5) and independent of [Cs]. In the region of 3\ifmmode\times\else\texttimes\fi{}

{10}^{14}

to 1\ifmmode\times\else\texttimes\fi{}

{10}^{15}

${\mathrm{cm}}^{\ensuremath{-}3}$ in number densities, the light-narrowing effect decreases with increasing [Cs]. At high cesium number densities ([Cs]> 1\ifmmode\times\else\texttimes\fi{}

{10}^{15}

${\mathrm{cm}}^{\ensuremath{-}3}$) this light-narrowing effect almost completely disappears. In the limit of low-radio-frequency power the magnetic resonance linewidths for focused and unfocused dye laser beam are nearly the same. Experimental observations on this new effect are presented in detail. In the latter part of this paper a self-contained theoretical treatment of the light-narrowing effect is developed. Using Bloch equations in the presence of optical pumping, spin relaxation (diffusion, electron randomization), rapid spin exchange, and radio-frequency magnetic field, expressions for magnetic resonance line shapes are derived. In general, we find good agreement between our experimental results and the theory.

Narrowing of magnetic-resonance lines in a dense optically pumped alkali-metal vapor

{(}^{87}

Rb) has been observed. This observation is shown to be a result of optical pumping with a monochromatic light source tuned such that the real part of the vapor polarizability, which is responsible for light shifts, is essentially zero. A model based on the Bloch equations is used to describe the observed narrowing effect, and results of numerical calculations based on this model are presented. The results agree qualitatively with observations, and show correctly the disappearance of the effect at low light levels. This narrowing effect is of importance to the development of precision frequency standards and magnetometers utilizing monochromatic light sources (such as semiconductor lasers).